Method for transmitting wake-up packet in communications system, and device

ABSTRACT

This application provides a method for transmitting a wake-up packet in a communications system and a device. The communications system includes a transmit end device and a receive end device. The receive end device includes a wake-up receiver and a main transceiver. The method includes: sending, by the transmit end device, a first wake-up packet WUP to the wake-up receiver by using a first data rate; determining, by the transmit end device, a second data rate; and sending, by the transmit end device, a second WUP to the wake-up receiver by using the second data rate. The transmit end device can determine a proper data rate for sending a wake-up packet based on a specific transmission condition in a communication process, thereby improving transmission efficiency of the wake-up packet.

This application claims priority to Chinese Patent Application No.201610674267.8, filed with the Chinese Patent Office on Aug. 15, 2016and entitled “METHOD FOR TRANSMITTING WAKE-UP PACKET IN COMMUNICATIONSSYSTEM, AND DEVICE”, which is incorporated herein by reference in itsentirety.

TECHNICAL FIELD

Embodiments of this application relates to the communications field, andmore specifically, to a method for transmitting a wake-up packet in acommunications system, and a device.

BACKGROUND

A device deployed in a communications system usually needs a relativelylong service life, which requires that the device have extremely lowpower consumption. A direct method for reducing power consumption is toprevent receive and transmit links of the device from being in an activestate all the time. For the transmit link, the device may autonomouslycontrol itself to wake up in the active state when there is data thatneeds to be sent. For the receive link, a commonly used method is thatthe device is always in a sleep state, and is woken up when there isdata that needs to be received. Because the device cannot determine atime at which data needs to be received, sleep efficiency and a datatransmission latency both need to be considered when a sleep/wake-upmode is designed.

In a sleep/wake-up mode, a wake-up radio (Wake Up Radio, “WUR” forshort) with low power consumption is introduced. The WUR maycontinuously perform link listening at extremely low power, and afterdetecting a wake-up packet, wake up a main radio to perform normal dataexchange. In this sleep/wake-up mode, how to improve efficiency oftransmitting the wake-up packet is an urgent problem needing to beresolved.

SUMMARY

This application provides a method for transmitting a wake-up packet ina communications system, and a device, to improve efficiency oftransmitting a wake-up packet in a communications system.

According to a first aspect, a method for transmitting a wake-up packetin a communications system is provided. The communications systemincludes a transmit end device and a receive end device, the receive enddevice includes a wake-up receiver and a main transceiver, and themethod includes: sending, by the transmit end device, a first wake-uppacket WUP to the wake-up receiver by using a first data rate;determining, by the transmit end device, a second data rate; andsending, by the transmit end device, a second WUP to the wake-upreceiver by using the second data rate.

Therefore, according to the method for transmitting a wake-up packet ina communications system in this application, the transmit end device cansend wake-up packets to the receive end device by using different datarates, so that the transmit end device can determine, based on aspecific transmission condition in a communication process, a properdata rate for sending a wake-up packet, thereby improving efficiency oftransmitting the wake-up packet.

With reference to the first aspect, in a first possible implementationof the first aspect, the sending, by the transmit end device, a firstwake-up packet to the wake-up receiver by using a first data rateincludes: sending, by the transmit end device, the first WUP to thewake-up receiver by using a first symbol rate; and the determining, bythe transmit end device, a second data rate, and sending, by thetransmit end device, a second WUP to the wake-up receiver by using thesecond data rate includes: determining, by the transmit end device, asecond symbol rate; and sending, by the transmit end device, the secondWUP to the wake-up receiver by using the second symbol rate.

With reference to the first aspect or the first possible implementationof the first aspect, in a second possible implementation of the firstaspect, the sending, by the transmit end device, a first wake-up packetWUP to the wake-up receiver by using a first data rate includes:sending, by the transmit end device, the first WUP to the wake-upreceiver by using a first modulation and coding scheme; and thedetermining, by the transmit end device, a second data rate, andsending, by the transmit end device, a second WUP to the wake-upreceiver by using the second data rate includes: determining, by thetransmit end device, a second modulation and coding scheme; and sending,by the transmit end device, the second WUP to the wake-up receiver byusing the second modulation and coding scheme.

It may be understood that in this application, that the data rates usedwhen the transmit end device transmits the wake-up packets at the twotimes are different may be specifically as follows: The symbol ratesused when the wake-up packets are transmitted at the two times aredifferent, and/or the modulation and coding schemes used when thewake-up packets are transmitted at the two times are different.

With reference to the first aspect, or either of the first or the secondpossible implementation of the first aspect, in a third possibleimplementation of the first aspect, the determining, by the transmit enddevice, a second data rate includes: determining, by the transmit enddevice, the second data rate based on a data rate used when the transmitend device sends data to the main transceiver.

With reference to the first aspect, or either of the first or the secondpossible implementation of the first aspect, in a fourth possibleimplementation of the first aspect, the determining, by the transmit enddevice, a second data rate includes: determining, by the transmit enddevice, the second data rate based on an operating frequency band of themain transceiver and/or an operating frequency band of the wake-upreceiver.

With reference to the first aspect, or either of the first or the secondpossible implementation of the first aspect, in a fifth possibleimplementation of the first aspect, the determining, by the transmit enddevice, a second data rate includes: determining, by the transmit enddevice, a symbol length corresponding to the second data rate based on amultipath delay spread.

Optionally, the multipath delay spread is a multipath delay spread in ashort range (an indoor environment), or the multipath delay spread is amultipath delay spread in a long range (an outdoor environment), or themultipath delay spread is a multipath delay spread in a currentcommunication environment.

With reference to the first aspect, or either of the first or the secondpossible implementation of the first aspect, in a sixth possibleimplementation of the first aspect, the determining, by the transmit enddevice, a second data rate includes: receiving, by the transmit enddevice, feedback information sent by the receive end device by using themain transceiver; and determining, by the transmit end device, thesecond data rate based on the feedback information.

Optionally, the feedback information sent by the receive end device tothe transmit end device by using the main transceiver includesinformation used to indicate a data rate expected by the receive enddevice.

With reference to the sixth possible implementation of the first aspect,in a seventh possible implementation of the first aspect, the feedbackinformation includes first information used to indicate asignal-to-noise ratio on an operating frequency of the main transceiverand/or the wake-up receiver; and the determining, by the transmit enddevice, the second data rate based on the feedback information includes:determining, by the transmit end device, the second data rate based onthe first information and a correspondence between a signal-to-noiseratio and a data rate.

In this way, a feedback mechanism in 802.11 may be reused to simplifyimplementation of the receive end device.

With reference to the sixth possible implementation of the first aspect,in an eighth possible implementation of the first aspect, the feedbackinformation includes second information used to indicate a power of thefirst WUP when the first WUP arrives at the wake-up receiver, and thedetermining, by the transmit end device, the second data rate based onthe feedback information includes: determining, by the transmit enddevice, the second data rate based on the second information and apreset power threshold; or

the feedback information includes third information used to indicate asignal-to-noise ratio of the first WUP at the wake-up receiver, and thedetermining, by the transmit end device, the second data rate based onthe feedback information includes: determining, by the transmit enddevice, the second data rate based on the third information and a presetsignal-to-noise ratio threshold; or

the feedback information includes fourth information used to indicate apacket error rate of the first WUP at the wake-up receiver, and thedetermining, by the transmit end device, the second data rate based onthe feedback information includes: determining, by the transmit enddevice, the second data rate based on the fourth information and apreset packet error rate threshold.

With reference to any one of the sixth to the eighth possibleimplementations of the first aspect, in a ninth possible implementationof the first aspect, the receiving, by the transmit end device, feedbackinformation sent by the receive end device by using the main transceiverincludes: receiving, by the transmit end device, a medium access controlMAC frame sent by the receive end device by using the main transceiver,where the MAC frame carries the feedback information.

Optionally, the MAC frame includes an information element (InformationElement, IE), the IE includes an information field, and the informationfield carries the feedback information.

With reference to the ninth possible implementation of the first aspect,in a tenth possible implementation of the first aspect, the receiving,by the transmit end device, a medium access control MAC frame sent bythe receive end device by using the main transceiver includes:receiving, by the transmit end device, a quality of service QoS dataframe sent by the receive end device by using the main transceiver,where the QoS data frame includes a high throughput control field, andthe high throughput control field carries the feedback information; orreceiving, by the transmit end device, a QoS null frame sent by thereceive end device by using the main transceiver, where the QoS nullframe includes a high efficiency aggregated control field, and the highefficiency aggregated control field carries the feedback information; orreceiving, by the transmit end device, a beamforming report sent by thereceive end device by using the main transceiver, where the beamformingreport includes a feedback field, and the feedback field carries thefeedback information.

With reference to the first aspect, or any one of the first to the tenthpossible implementations of the first aspect, in an eleventh possibleimplementation of the first aspect, the sending, by the transmit enddevice, a second WUP to the wake-up receiver by using the second datarate includes: modulating, by the transmit end device, an informationbit in the second WUP into a plurality of modulation symbols based onthe second data rate, where the plurality of modulation symbols includea first modulation symbol whose symbol energy is 0 and a secondmodulation symbol whose symbol energy is not 0; and sending, by thetransmit end device, the plurality of modulation symbols to the wake-upreceiver.

With reference to the eleventh possible implementation of the firstaspect, in a twelfth possible implementation of the first aspect, thesending, by the transmit end device, the plurality of modulation symbolsto the wake-up receiver includes: sending, by the transmit end device,the plurality of modulation symbols to the wake-up receiver in a mannerof sending one placeholder symbol to the wake-up receiver each time thetransmit end device sends a first preset quantity of modulation symbolsto the wake-up receiver, where the placeholder symbol does not carry aninformation bit, and a symbol energy of the placeholder symbol is not 0;or sending, by the transmit end device, the plurality of modulationsymbols to the wake-up receiver in a manner of sending one placeholdersymbol to the wake-up receiver each time the transmit end device sends asecond preset quantity of first modulation symbols to the wake-upreceiver, where the placeholder symbol does not carry an informationbit, and a symbol energy of the placeholder symbol is not 0.

In this way, the following case may be avoided: Due to an excessivelylong channel idle time, another receive end device preempts a channel,affecting transmission of the wake-up packet. Therefore, efficiency oftransmitting the wake-up packet is improved.

With reference to the first aspect or any one of the first to thetwelfth possible implementations of the first aspect, in a thirteenthpossible implementation of the first aspect, the second WUP includes asignaling field and a data field that are arranged in a sending timesequence, and the signaling field carries indication information used toindicate the second data rate.

With reference to the thirteenth possible implementation of the firstaspect, in a fourteenth possible implementation of the first aspect, thesecond WUP further includes a redundancy field, and a sending time ofthe redundancy field is after a sending time of the signaling field andbefore a sending time of the data field.

In this way, the receive end device may adjust the data rate within atime period in which the transmit end device sends the redundancy field,to successfully receive and parse the data field sent by the transmitend device.

With reference to the first aspect or any one of the first to thetwelfth possible implementations of the first aspect, in a fifteenthpossible implementation of the first aspect, the second WUP includes apreamble field and a data field that are in a sending time sequence, sothat the receive end device determines the second data rate based on apreamble mode corresponding to the preamble field and a presetcorrespondence, where the preset correspondence includes acorrespondence between a preamble mode and a data rate.

With reference to the first aspect or any one of the first to thefifteenth possible implementations of the first aspect, in a sixteenthpossible implementation of the first aspect, the second WUP includes aMAC header field, the MAC header field includes an identifierinformation field, the identifier information field is used to carryidentifier information of the receive end device, and the method furtherincludes: determining, by the transmit end device based on the seconddata rate, a quantity of information bits included in the identifierinformation field, where the quantity of information bits included inthe identifier information field is positively correlated with amagnitude of the second data rate.

In this way, transmission overheads caused by excessive information bitsincluded in the identifier information field can be avoided.

Optionally, the MAC header field includes a field used to indicate thequantity of information bits included in the identifier informationfield, so that the receive end device determines the quantity ofinformation bits in the identifier information field based oninformation carried in the field.

According to a second aspect, a method for transmitting a wake-up packetin a communications system is provided. The communications systemincludes a transmit end device and a receive end device, the receive enddevice includes a wake-up receiver and a main transceiver, and themethod includes: receiving, by the receive end device by using thewake-up receiver, a first wake-up packet WUP sent by the transmit enddevice by using a first data rate; receiving, by the receive end deviceby using the wake-up receiver, a second WUP sent by the transmit enddevice by using a second data rate; determining, by the receive enddevice, the second data rate; and parsing, by the receive end device,the second WUP based on the second data rate.

Therefore, according to the method for transmitting a wake-up packet ina communications system in this application, the receive end devicereceives wake-up packets sent by the transmit end device by usingdifferent data rates, and the transmit end device can determine, basedon a specific transmission condition in a communication process, aproper data rate for sending a wake-up packet, thereby improvingefficiency of transmitting the wake-up packet.

With reference to the second aspect, in a first possible implementationof the second aspect, the receiving, by the receive end device by usingthe wake-up receiver, a first wake-up packet WUP sent by the transmitend device by using a first data rate includes: receiving, by thereceive end device by using the wake-up receiver, the first WUP sent bythe transmit end device by using a first symbol rate; the receiving, bythe receive end device by using the wake-up receiver, a second WUP sentby the transmit end device by using a second data rate includes:receiving, by the receive end device by using the wake-up receiver, thesecond WUP sent by the transmit end device by using a second symbolrate; the determining, by the receive end device, the second data rateincludes: determining, by the receive end device, the second symbolrate; and the parsing, by the receive end device, the second WUP basedon the second data rate includes: parsing, by the receive end device,the second WUP based on the second symbol rate.

With reference to the second aspect or the first possible implementationof the second aspect, in a second possible implementation of the secondaspect, the receiving, by the receive end device by using the wake-upreceiver, a first wake-up packet WUP sent by the transmit end device byusing a first data rate includes: receiving, by the receive end deviceby using the wake-up receiver, the first WUP sent by the transmit enddevice by using a first modulation and coding scheme; the receiving, bythe receive end device by using the wake-up receiver, a second WUP sentby the transmit end device by using a second data rate includes:receiving, by the receive end device by using the wake-up receiver, thesecond WUP sent by the transmit end device by using the secondmodulation and coding scheme; the determining, by the receive enddevice, the second data rate includes: determining, by the receive enddevice, the second modulation and coding scheme; and the parsing, by thereceive end device, the second WUP based on the second data rateincludes: parsing, by the receive end device, the second WUP based onthe second modulation and coding scheme.

With reference to the second aspect, or either of the first or thesecond possible implementation of the second aspect, in a third possibleimplementation of the second aspect, the method further includes:sending, by the receive end device, feedback information to the transmitend device by using the main transceiver, so that the transmit enddevice determines the second data rate based on the feedbackinformation.

With reference to the third possible implementation of the secondaspect, in a fourth possible implementation of the second aspect, thefeedback information includes first information used to indicate asignal-to-noise ratio on an operating frequency of the main transceiverand/or the wake-up receiver, so that the transmit end device determinesthe second data rate based on the first information and a correspondencebetween a signal-to-noise ratio and a data rate.

With reference to the third possible implementation of the secondaspect, in a fifth possible implementation of the second aspect, thefeedback information includes second information used to indicate apower of the first WUP when the first WUP arrives at the wake-upreceiver, so that the transmit end device determines the second datarate based on the second information and a preset power threshold; orthe feedback information includes third information used to indicate asignal-to-noise ratio of the first WUP at the wake-up receiver, so thatthe transmit end device determines the second data rate based on thethird information and a preset signal-to-noise ratio threshold; or thefeedback information includes fourth information used to indicate apacket error rate of the first WUP at the wake-up receiver, so that thetransmit end device determines the second data rate based on the fourthinformation and a preset packet error rate threshold.

With reference to any one of the third to the fifth possibleimplementations of the second aspect, in a sixth possible implementationof the second aspect, the sending, by the receive end device, feedbackinformation to the transmit end device by using the main transceiverincludes: sending, by the receive end device, a medium access controlMAC frame to the transmit end device by using the main transceiver,where the MAC frame carries the feedback information.

With reference to the sixth possible implementation of the secondaspect, in a seventh possible implementation of the second aspect, thesending, by the receive end device, a medium access control MAC frame tothe transmit end device by using the main transceiver includes: sending,by the receive end device, a quality of service QoS data frame to thetransmit end device by using the main transceiver, where the QoS dataframe includes a high throughput control field, and the high throughputcontrol field carries the feedback information; or sending, by thereceive end device, a QoS null frame to the transmit end device by usingthe main transceiver, where the QoS null frame includes a highefficiency aggregated control field, and the high efficiency aggregatedcontrol field carries the feedback information; or sending, by thereceive end device, a beamforming report to the transmit end device byusing the main transceiver, where the beamforming report includes afeedback field, and the feedback field carries the feedback information.

With reference to the second aspect or any one of the first to theseventh possible implementations of the second aspect, in an eighthpossible implementation of the second aspect, the receiving, by thereceive end device by using the wake-up receiver, a second WUP sent bythe transmit end device by using a second data rate includes: receiving,by the receive end device by using the wake-up receiver, a plurality ofmodulation symbols sent by the transmit end device, where the pluralityof modulation symbols are obtained by the transmit end device bymodulating an information bit in the second WUP based on the second datarate, and the plurality of modulation symbols include a first modulationsymbol whose symbol energy is 0 and a second modulation symbol whosesymbol energy is not 0.

With reference to the eighth possible implementation of the secondaspect, in a ninth possible implementation of the second aspect, theplurality of modulation symbols are sent by the transmit end device in amanner of sending one placeholder symbol to the wake-up receiver eachtime the transmit end device sends a first preset quantity of modulationsymbols to the wake-up receiver, the placeholder symbol does not carryan information bit, and a symbol energy of the placeholder symbol is not0; and the receiving, by the receive end device by using the wake-upreceiver, a plurality of modulation symbols sent by the transmit enddevice includes: receiving, by the receive end device by using thewake-up receiver, the plurality of modulation symbols in a manner ofignoring the placeholder symbol each time the receive end devicereceives the first preset quantity of modulation symbols.

With reference to the eighth possible implementation of the secondaspect, in a ninth possible implementation of the second aspect, theplurality of modulation symbols are sent by the transmit end device in amanner of sending one placeholder symbol to the wake-up receiver eachtime the transmit end device sends a second preset quantity of secondmodulation symbols to the wake-up receiver, the placeholder symbol doesnot carry an information bit, and a symbol energy of the placeholdersymbol is not 0; and the receiving, by the receive end device by usingthe wake-up receiver, a plurality of modulation symbols sent by thetransmit end device includes: receiving, by the receive end device byusing the wake-up receiver, the plurality of modulation symbols in amanner of ignoring the placeholder symbol each time the receive enddevice receives the second preset quantity of second modulation symbols.

With reference to the second aspect, or any one of the first to theninth possible implementations of the second aspect, in a tenth possibleimplementation of the second aspect, the second WUP includes a signalingfield and a data field that are arranged in a sending time sequence, andthe signaling field carries indication information used to indicate thesecond data rate; and the determining, by the receive end device, thesecond data rate includes: determining, by the receive end device, thesecond data rate based on the indication information.

With reference to the tenth possible implementation of the secondaspect, in an eleventh possible implementation of the second aspect, thesecond WUP further includes a redundancy field, and a sending time ofthe redundancy field is after a sending time of the signaling field andbefore a sending time of the data field.

With reference to the second aspect or any one of the first to the ninthpossible implementations of the second aspect, in a twelfth possibleimplementation of the second aspect, the second WUP includes a preamblefield and a data field that are in a sending time sequence; and thedetermining, by the receive end device, the second data rate includes:determining, by the receive end device, the second data rate based on apreamble mode corresponding to the preamble field and a presetcorrespondence, where the preset correspondence includes acorrespondence between a preamble mode and a data rate.

With reference to the second aspect or any one of the first to thetwelfth possible implementations of the second aspect, in a thirteenthpossible implementation of the second aspect, the second WUP includes aMAC header field, the MAC header field includes an identifierinformation field, the identifier information field is used to carryidentifier information of the receive end device, and a quantity ofinformation bits included in the identifier information field ispositively correlated with a magnitude of the second data rate.

According to a third aspect, a method for transmitting a wake-up packetin a communications system is provided. The communications systemincludes a transmit end device and a receive end device, the receive enddevice includes a wake-up receiver and a main transceiver, and themethod includes: generating, by the transmit end device, M wake-uppackets WUPs; and sending, by the transmit end device, an i^(th) WUP toa wake-up receiver of an i^(th) receive end device in M receive enddevices, where transmission resources occupied by the transmit enddevice to send WUPs to wake-up receivers of any two receive end devicescorrespond to a same time and different frequencies, i=1, 2, . . . , M,and M is a positive integer greater than 1.

Therefore, according to the method for transmitting a wake-up packet ina communications system in this embodiment of this application, thetransmit end device simultaneously sends wake-up packets to a pluralityof receive end devices, so that efficiency of transmitting the wake-uppacket can be improved.

With reference to the third aspect, in a first possible implementationof the third aspect, the method further includes: generating, by thetransmit end device, a plurality of symbols corresponding to aninformation bit in the i^(th) WUP, where the plurality of symbolsinclude a first symbol whose symbol energy is not 0 and a second symbolwhose symbol energy is 0, and a method for generating the first symbolis: determining an i^(th) frequency domain filling sequence; filling thei^(th) frequency domain filling sequence on a plurality of subcarriersat an operating frequency of the wake-up receiver of the i^(th) receiveend device, to obtain an i^(th) frequency domain signal; and performingan inverse fast Fourier transform IFFT on the i^(th) frequency domainsignal to obtain the symbol carrying an information bit 1.

With reference to the first possible implementation of the third aspect,in a second possible implementation of the third aspect, the determiningan i^(th) frequency domain filling sequence includes: twiddling afrequency domain pre-filling sequence based on an i^(th) twiddle factorin M twiddle factors, to obtain the i^(th) frequency domain fillingsequence, where at least two twiddle factors in the M twiddle factorsare different.

With reference to the first possible implementation of the third aspect,in a third possible implementation of the third aspect, the determiningan i^(th) frequency domain filling sequence includes: generating a fullbandwidth sequence; and determining the i^(th) filling sequence based onthe full bandwidth sequence.

With reference to the first possible implementation of the third aspect,in a fourth possible implementation of the third aspect, a quantity of0s between two neighboring non-zero values in the i^(th) frequencydomain filling sequence is a preset quantity.

With reference to the first possible implementation of the third aspect,in a fifth possible implementation of the third aspect, the determiningan i^(th) frequency domain filling sequence includes: generating ani^(th) time domain filling sequence, where values in the i^(th) timedomain filling sequence have a same amplitude; and performing a Fouriertransform FFT on the i^(th) time domain filling sequence to obtain thei^(th) frequency domain filling sequence.

According to a fourth aspect, a transmit end device is provided. Thetransmit end device is configured to perform the method in the firstaspect or any possible implementation of the first aspect. Specifically,the transmit end device includes a function module configured to performthe method in the first aspect or any possible implementation of thefirst aspect.

According to a fifth aspect, a receive end device is provided. Thereceive end device is configured to perform the method in the secondaspect or any possible implementation of the second aspect.Specifically, the receive end device includes a function moduleconfigured to perform the method in the second aspect or any possibleimplementation of the second aspect.

According to a sixth aspect, a transmit end device is provided. Thetransmit end device is configured to perform the method in the thirdaspect or any possible implementation of the third aspect. Specifically,the transmit end device includes a function module configured to performthe method in the third aspect or any possible implementation of thethird aspect.

According to a seventh aspect, a transmit end device is provided. Thetransmit end device includes a processor, a memory, and a transceiver.The processor, the memory, and the transceiver are connected by using abus system. The memory is configured to store an instruction. Theprocessor is configured to invoke the instruction stored in the memoryto control the transceiver to receive or send information, to enable thetransmit end device to perform the method in the first aspect or anypossible implementation of the first aspect.

According to an eighth aspect, a receive end device is provided. Thereceive end device includes a processor, a memory, a wake-up receiver,and a main transceiver. The processor, the memory, the wake-up receiver,and the main transceiver are connected by using a bus system. The memoryis configured to store an instruction. The processor is configured toinvoke the instruction stored in the memory to control the wake-upreceiver to receive information and control the main transceiver toreceive or send information, to enable the receive end device to performthe method in the second aspect or any possible implementation of thesecond aspect.

According to a ninth aspect, a transmit end device is provided. Thetransmit end device includes a processor, a memory, and a transceiver.The processor, the memory, and the transceiver are connected by using abus system. The memory is configured to store an instruction. Theprocessor is configured to invoke the instruction stored in the memoryto control the transceiver to receive or send information, to enable thetransmit end device to perform the method in the third aspect or anypossible implementation of the third aspect.

According to a tenth aspect, a computer readable medium is provided. Thecomputer readable medium is configured to store a computer program. Thecomputer program includes an instruction used to perform the method inthe first aspect or any possible implementation of the first aspect.

According to an eleventh aspect, a computer readable medium is provided.The computer readable medium is configured to store a computer program.The computer program includes an instruction used to perform the methodin the second aspect or any possible implementation of the secondaspect.

According to a twelfth aspect, a computer readable medium is provided.The computer readable medium is configured to store a computer program.The computer program includes an instruction used to perform the methodin the third aspect or any possible implementation of the third aspect.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of an application scenario according to anembodiment of this application;

FIG. 2 is a schematic diagram of a possible collaborative operatingmanner of a wake-up receiver and a main transceiver according to anembodiment of this application;

FIG. 3 is a schematic structural diagram of a wake-up packet accordingto an embodiment of this application;

FIG. 4 is a schematic flowchart of a method for transmitting a wake-uppacket in a communications system according to an embodiment of thisapplication;

FIG. 5 is a schematic diagram of two different symbol lengths accordingto an embodiment of this application;

FIG. 6 is another schematic flowchart of a method for transmitting awake-up packet in a communications system according to an embodiment ofthis application;

FIG. 7 is a schematic structural diagram of a QoS data frame accordingto an embodiment of this application;

FIG. 8 is a schematic structural diagram of a high efficiency aggregatedcontrol field according to an embodiment of this application;

FIG. 9 is a schematic structural diagram of a beamforming reportaccording to an embodiment of this application;

FIG. 10 is a schematic structural diagram of an information elementaccording to an embodiment of this application;

FIG. 11 is a schematic structural diagram of an M-BA frame according toan embodiment of this application;

FIG. 12 is a schematic structural diagram of a trigger frame accordingto an embodiment of this application;

FIG. 13 is a schematic structural diagram of a wake-up packet accordingto another embodiment of this application;

FIG. 14 is a schematic structural diagram of a wake-up packet accordingto still another embodiment of this application;

FIG. 15 is a schematic diagram of a method for distinguishing betweenreceive end devices according to an embodiment of this application;

FIG. 16 is a schematic diagram of a method in which a transmit enddevice simultaneously sends wake-up packets to a plurality of receiveends according to an embodiment of this application;

FIG. 17 is a schematic block diagram of a transmit end device accordingto an embodiment of this application;

FIG. 18 is a schematic block diagram of a receive end device accordingto an embodiment of this application;

FIG. 19 is a schematic block diagram of a transmit end device accordingto another embodiment of this application; and

FIG. 20 is a schematic block diagram of a receive end device accordingto another embodiment of this application.

DESCRIPTION OF EMBODIMENTS

FIG. 1 is a schematic diagram of an application scenario according to anembodiment of this application. A wireless local area network (WirelessLocal Area Network, WLAN) shown in FIG. 1 includes a transmit end device(for example, an access point (Access Point, AP) shown in FIG. 1) and areceive end device (for example, a station (Station, STA) shown in FIG.1). The AP is responsible for performing bidirectional communicationwith a plurality of STAs. For example, the AP shown in FIG. 1 sendsdownlink data to the STA (for example, a STA 1 and a STA 2 in FIG. 1),or the AP receives uplink data from the STA (for example, a STA 3 inFIG. 1). It should be understood that, a quantity of APs and a quantityof STAs shown in FIG. 1 are only examples, and the WLAN may include anyquantity of APs and any quantity of STAs.

FIG. 2 is a schematic diagram of a possible collaborative operatingmanner of a wake-up receiver and a main transceiver according to anembodiment of this application. As shown in FIG. 2, a receive end deviceincludes a main transceiver 2 and a wake-up receiver, and a transmit enddevice includes a main transceiver 1. To implement low powerconsumption, a circuit structure of the wake-up receiver is relativelysimple, and may include only an energy detection (Energy Detect) partand a radio frequency (Radio Frequency, RF) part. After the maintransceiver 2 of the receive end device enters deep sleep, the wake-upreceiver with low power consumption wakes up and starts operating. Ifthe transmit end device needs to communicate with the receive enddevice, the transmit end device first sends a wake-up packet (Wake UpPacket, WUP) to the wake-up receiver of the receive end device. Aftercorrectly receiving the WUP sent to the wake-up receiver, the wake-upreceiver wakes up the main transceiver 2 of the receive end device, andthen enters a sleep state; and the transmit end device communicates withthe main transceiver 2 by using the main transceiver 1. After completingcommunication with the transmit end device, the main transceiver 2enters the sleep state, and the wake-up receiver wakes up and startslistening for whether there is a WUP sent to the wake-up receiver, so asto wake up the main transceiver 2 when receiving the WUP.

It should be understood that, a main transceiver of a receive end devicecan be woken up only by a wake-up receiver corresponding to the receiveend device. When no special description is provided in thisspecification, the main transceiver and the wake-up receiver arerespectively a main transceiver and a wake-up receiver of a same receiveend device. When the receive end device is a STA, a correspondingtransmit end device is an AP; or when the receive end device is an AP, acorresponding receive end device is a STA.

It should be further understood that the WUP mentioned in thisembodiment of this application may also be referred to as a wake-upframe (Wake Up Frame). FIG. 3 shows a possible structure of a WUPaccording to an embodiment of this application. The WUP includes alegacy 802.11 preamble (Legacy 802.11 Preamble) and a WUP payload(Payload). The WUP payload includes a wake-up preamble (Wake UpPreamble), a medium access control header (Medium Access Control Header,MAC Header), a frame body (Frame Body), and a frame check sequence(Frame Check Sequence, FCS). The WUP payload may also be referred to asa data part (Data Part).

The legacy 802.11 preamble is used to protect a subsequent part of theWUP from being interfered by a legacy 802.11 device, a function of thewake-up preamble is used by a receive end device to identify a WUPsignal, the MAC header part may carry information such as an address ofthe receive end device and that of a transmit end device, the frame bodyis used to carry some other information, and the FCS part is used toensure that data received by the receive end device is the same as datasent by the transmit end device.

With reference to specific embodiments, the following describes a methodfor transmitting a wake-up packet in a communications system accordingto an embodiment of this application. It should be noted that, in thefollowing embodiments, a data rate refers to an amount of information (aquantity of bits) transmitted on a channel within a unit time, and asymbol rate refers to a quantity of symbols transmitted on a channelwithin a unit time. That a transmit end device sends a wake-up packet toa wake-up receiver of a receive end device may alternatively bedescribed as that the transmit end device sends the wake-up packet tothe receive end device.

FIG. 4 is a schematic flowchart of a method for transmitting a wake-uppacket in a communications system according to an embodiment of thisapplication. The communications system includes a transmit end deviceand a receive end device, and the receive end device includes a wake-upreceiver and a main transceiver. As shown in FIG. 4, a method 100includes:

S110. The transmit end device sends a first wake-up packet WUP to thewake-up receiver by using a first data rate.

S120. The transmit end device determines a second data rate.

S130. The transmit end device sends a second WUP to the wake-up receiverby using the second data rate.

Optionally, in an example, in S110, a possible implementation in whichthe transmit end device sends the first WUP to the wake-up receiver byusing the first data rate is as follows: The transmit end device sendsthe first WUP to the wake-up receiver by using a first symbol rate.Correspondingly, in S120, the transmit end device determines a secondsymbol rate; and in S130, the transmit end device sends the second WUPto the wake-up receiver by using the second symbol rate.

To be specific, a specific implementation in which the transmit enddevice sends a WUP to the wake-up receiver of the receive end device byusing a variable data rate is as follows: The transmit end device sendsthe WUP to the wake-up receiver of the receive end device by using avariable symbol rate.

It may be understood that the variable symbol rate may be specificallyembodied as a variable symbol length, for example, t1, t2, or t3.

In the foregoing embodiment, a manner of generating a variable symbollength is: defining a minimum symbol length as t μs, and determiningother symbol lengths based on t. For example, t1=t, t2=2t, t3=3t, andthe like may be defined. FIG. 5 is a schematic diagram of two differentsymbol lengths according to an embodiment of this application.Optionally, a value oft may be specified as one of the following values:1.6 μs, 2 μs, 2.4 μs, 3.2 μs, and 4 μs. Alternatively, the minimumsymbol length is defined as t μs, and symbols of a plurality of lengthsare generated by using different spreading codes. Specifically, aplurality of spreading codes whose lengths are 1, 2, 4, 8, and the likemay be defined, and different symbol lengths correspond to differentspreading codes. For example, when an information bit is 1, if a lengthof a spreading code is 1, a symbol used to carry the information bit 1includes one symbol whose length is t μs; or if a length of a spreadingcode is 4, a symbol used to carry the information bit 1 includes foursymbols whose lengths are t μs.

In this embodiment of this application, optionally, before each sendingof the WUP, the transmit end device needs to determine a symbol length,and the symbol length determined by the transmit end device needs tomeet the following condition: A power of the WUP when the WUP arrives atthe receive end device is not less than a preset power threshold (or anaverage power of symbols in the WUP when the symbols arrive at thereceive end device is not less than a preset power threshold), or apacket error rate (Packet Error Rate, PER) of demodulation of the WUP atthe receive end device is less than a preset packet error rate threshold(or an average symbol error rate of symbols in the WUP at the receiveend device is less than a preset symbol error rate threshold), or asignal-to-noise ratio of the WUP at the receive end device is not lessthan a preset signal-to-noise ratio threshold (or an averagesignal-to-noise ratio of symbols in the WUP at the receive end device isnot less than a preset signal-to-noise ratio threshold). It is assumedthat a symbol length meeting the foregoing condition is T1. In thiscase, the transmit end device determines that a symbol length T used forsending the WUP this time is greater than or equal to T1.

Further, the transmit end device determines the symbol length based on amultipath delay spread, so that the symbol length determined by thetransmit end device is not less than a multipath delay spread in a shortrange (an indoor environment), or not less than a multipath delay spreadin a long range (an outdoor environment), or not less than a multipathdelay spread in a current communication environment. It is assumed thata symbol length meeting the foregoing constraint condition is T2. Thetransmit end device may determine a value greater than or equal to amaximum value in T1 and T2 as a symbol length T used for sending the WUPthis time. Alternatively, the symbol length T determined by the transmitend device meets T₁+T₂≥T≥T₁ or T₁+T₂≥T≥max(T₁, T₂). After receiving eachsymbol, the corresponding receive end device discards symbols receivedin previous x μs or T2 μs to avoid interference between symbols.

In the foregoing embodiment, optionally, the transmit end device maymultiplex an OFDM transmitter. When the symbol length is less than asymbol length in an existing standard, a symbol output by an inversefast Fourier transform (Inverse fast Fourier transform, IFFT) module maybe truncated by using an existing truncation (Truncate) module in theOFDM transmitter, or the symbol output by the IFFT module may beextracted by using a down-sampling module, or a shorter symbol may begenerated by directly using a smaller-point IFFT. However, thisapplication is not limited thereto.

Optionally, in another example, in S110, a possible implementation inwhich the transmit end device sends the first WUP to the wake-upreceiver by using the first data rate is as follows: The transmit enddevice sends the first WUP to the wake-up receiver by using a firstmodulation and coding scheme. Correspondingly, in S120, the transmit enddevice determines a second modulation and coding scheme; and in S130,the transmit end device sends the second WUP to the wake-up receiver byusing the second modulation and coding scheme.

To be specific, a specific implementation in which the transmit enddevice sends a WUP to the wake-up receiver of the receive end device byusing a variable data rate is as follows: The transmit end device sendsthe WUP to the wake-up receiver of the receive end device by using avariable modulation and coding scheme.

It may be understood that variable coding and modulation may bespecifically embodied as a variable frequency modulation order and/or avariable phase modulation order and/or a variable amplitude modulationorder and/or a variable coding rate. For example, the variable frequencymodulation order and/or the variable phase modulation order and/or thevariable amplitude modulation order are/is binary amplitude shift keying(Amplitude-shift-keying, ASK) or 4ASK; or binary frequency shift keying(Frequency-shift-keying, FSK) FSK or 4FSK; or binary phase shift keying(Phase-shift-keying, PSK) or 4PSK; or quaternary quadrature amplitudemodulation (Quadrature Amplitude Modulation, QAM) or 16QAM. For example,the variable coding rate is 1/2 BCC coding, 3/4 BCC coding, or codingwith the variable coding rate.

In this embodiment of this application, optionally, before each sendingof the WUP, the transmit end device needs to determine a modulation andcoding scheme, and the modulation and coding scheme determined by thetransmit end device needs to meet the following condition: A power ofthe WUP when the WUP arrives at the receive end device is not less thana preset power threshold (or an average power of symbols in the WUP whenthe symbols arrive at the receive end device is not less than a presetpower threshold), or a packet error rate (Packet Error Rate, PER) ofdemodulation of the WUP at the receive end device is less than a presetpacket error rate threshold (or an average symbol error rate of symbolsin the WUP at the receive end device is less than a preset symbol errorrate threshold), or a signal-to-noise ratio of the WUP at the receiveend device is not less than a preset signal-to-noise ratio threshold (oran average signal-to-noise ratio of symbols in the WUP at the receiveend device is not less than a preset signal-to-noise ratio threshold).

Optionally, in another example, in S110, a possible implementation inwhich the transmit end device sends the first WUP to the wake-upreceiver by using the first data rate is as follows: The transmit enddevice sends the first WUP to the wake-up receiver by using a firstsymbol rate and a first modulation and coding scheme. Correspondingly,in S120, the transmit end device determines a second symbol rate and asecond modulation and coding scheme; and in S130, the transmit enddevice sends the second WUP to the wake-up receiver by using the secondsymbol rate and the second modulation and coding scheme.

To be specific, a specific implementation in which the transmit enddevice sends a WUP to the wake-up receiver of the receive end device byusing a variable data rate is as follows: The transmit end device sendsthe WUP to the wake-up receiver of the receive end device by using avariable symbol rate and a variable modulation and coding scheme.

The variable symbol rate and the variable modulation and coding schememay be specifically embodied as a variable symbol length+a variablefrequency modulation order and/or a variable phase modulation orderand/or a variable amplitude modulation order and/or a coding rate, forexample, t1+2ASK, t2+2ASK, or t2+4ASK. A specific example is as follows:4 μs+amplitude 0 indicates 0, and 4 μs+amplitude A indicates 1; 4μs+amplitude 0 indicates 00, 4 μs+amplitude A indicates 01, 4μs+amplitude 2 A indicates 10, and 4 μs+amplitude 3 A indicates 11; 2.4μs+amplitude 0 indicates 0, and 2.4 μs+amplitude A indicates 1; and 2.4μs+amplitude 0 indicates 00, 2.4 μs+amplitude A indicates 01, 2.4μs+amplitude 2 A indicates 10, and 2.4 μs+amplitude 3 A indicates 11.

In this embodiment of this application, optionally, before each sendingof the WUP, the transmit end device needs to determine a symbol lengthand a modulation and coding scheme, and the symbol length and themodulation and coding scheme determined by the transmit end device needto meet the following condition: A power of the WUP when the WUP arrivesat the receive end device is not less than a preset power threshold (oran average power of symbols in the WUP when the symbols arrive at thereceive end device is not less than a preset power threshold), or apacket error rate (Packet Error Rate, PER) of demodulation of the WUP atthe receive end device is less than a preset packet error rate threshold(or an average symbol error rate of symbols in the WUP at the receiveend device is less than a preset symbol error rate threshold), or asignal-to-noise ratio of the WUP at the receive end device is not lessthan a preset signal-to-noise ratio threshold (or an averagesignal-to-noise ratio of symbols in the WUP at the receive end device isnot less than a preset signal-to-noise ratio threshold).

In the foregoing embodiment, optionally, the transmit end device maymultiplex an OFDM transmitter. When the symbol length is less than asymbol length in an existing standard, a symbol output by an inversefast Fourier transform (Inverse fast Fourier transform, IFFT) module maybe truncated by using an existing truncation (Truncate) module in theOFDM transmitter, or the symbol output by the IFFT module may beextracted by using a down-sampling module, or a shorter symbol may begenerated by directly using a smaller-point IFFT. However, thisapplication is not limited thereto.

Optionally, in an embodiment, in S120, when determining the second datarate, the transmit end device determines the second data rate based on adata rate used when the transmit end device sends data to the maintransceiver. For example, the transmit end device sends data to the maintransceiver by using the first data rate. If the transmit end devicedetermines that the receive end device can correctly receive the data,the transmit end device considers that current channel quality isrelatively good, and may further increase the data rate used when thetransmit end device sends the data. Therefore, when sending the secondWUP, the transmit end device may send the wake-up packet to the wake-upreceiver by using a second data rate greater than the first data rate.Alternatively, the transmit end device sends data to the maintransceiver by using the first data rate. If the transmit end devicedetermines that the receive end device cannot correctly receive thedata, the transmit end device considers that current channel quality isrelatively poor, and needs to further decrease the data rate used whenthe transmit end device sends the data. Therefore, when sending thesecond WUP, the transmit end device may send the WUP to the wake-upreceiver by using a second data rate smaller than the first data rate.

Optionally, in another embodiment, in S120, when determining the seconddata rate, the transmit end device determines the second data rate basedon an operating frequency band of the main transceiver and/or anoperating frequency band of the wake-up receiver. For example, if themain transceiver operates on a 2.4 GHz frequency band and the wake-upreceiver operates on a 5 GHz frequency band, the transmit end devicesends the wake-up packet to the wake-up receiver at the first data rate.If the main transceiver operates on a 5 GHz frequency band and thewake-up receiver operates on a 2.4 GHz frequency band, the transmit enddevice sends the wake-up packet to the wake-up receiver at the seconddata rate. Alternatively, if the main transceiver and the wake-upreceiver operate on a same frequency band, the transmit end device sendsthe wake-up packet to the wake-up receiver at the first data rate. Ifthe main transceiver and the wake-up receiver operate on differentfrequency bands, the transmit end device sends the wake-up packet to thewake-up receiver at the second data rate.

Optionally, in another embodiment, as shown in FIG. 6, S120 specificallyincludes the following steps.

S121. The transmit end device receives feedback information sent by thereceive end device by using the main transceiver.

S122. The transmit end device determines the second data rate based onthe feedback information.

Optionally, in S121, the feedback information includes a data rate thatthe receive end device expects the transmit end device to use, and thetransmit end device may directly determine the data rate in the feedbackinformation as the second data rate.

Optionally, in S121, the feedback information includes first informationused to indicate a signal-to-noise ratio (signal-to-noise ratio, SNR) onan operating frequency of the main transceiver and/or an operatingfrequency of the wake-up receiver. Correspondingly, in S122, thetransmit end device determines the second data rate based on the firstinformation and a correspondence between a signal-to-noise ratio and adata rate.

Optionally, the correspondence between a signal-to-noise ratio and adata rate may be stored in the transmit end device in a form of a table.For example, if capabilities of all wake-up receivers are considered asthe same, for example, all the wake-up receivers have a channel codingcapability, or none of the wake-up receivers has a channel codingcapability, a possible correspondence between an SNR and a data rate maybe shown in Table 1.

TABLE 1 SNR Range Data Rate <snr_1 dB Rate 1 snr_1 dB to snr_2 dB Rate 2snr_2 dB to snr_3 dB Rate 3 >snr_3 dB Rate 4

If differences of the capabilities of the wake-up receivers areconsidered, for example, some wake-up receivers have the channel codingcapability, and the other wake-up receivers do not have the channelcoding capability, in this case, when performing energy reporting, thereceive end device needs to report whether the wake-up receiver of thereceive end device supports channel coding. When being associated withthe transmit end device, the receive end device may report whether thewake-up receiver of the receive end device supports channel coding; orin a process of communicating with the transmit end device by using themain transceiver, the receive end device may inform the transmit enddevice whether the wake-up receiver of the receive end device supportschannel coding. A possible correspondence between an SNR and a data rateis shown in Table 2.

TABLE 2 Data Rate Having a channel Having no channel SNR Range codingcapability coding capability <snr_1 dB Rate 1 Rate 1′ snr_1 dB to snr_2dB Rate 2 Rate 2′ snr_2 dB to snr_3 dB Rate 3 Rate 3′ >snr_3 dB Rate 4Rate 4′

Alternatively, a correspondence table between an SNR and a data rate maybe separately set for a wake-up receiver having a channel codingcapability and a wake-up receiver having no channel coding capability. Acorrespondence that is between an SNR and a data rate and thatcorresponds to a wake-up receiver having a channel coding capability isshown in Table 1. A correspondence that is between an SNR and a datarate and that corresponds to a wake-up receiver having no channel codingcapability is shown in Table 3.

TABLE 3 SNR Range Data Rate <snr_1 dB Rate 1′ snr_1 dB to snr_2 dB Rate2′ snr_2 dB to snr_3 dB Rate 3′ >snr_3 dB Rate 4′

Further, a group of modulation and coding schemes (Modulation and CodingScheme, MCS) may be specified for the wake-up receiver, and acorrespondence exists between a data rate and a modulation and codingscheme. A possible correspondence between a data rate and a modulationand coding scheme is shown in Table 4.

TABLE 4 MCS Scheme 0 Rate 1 1 Rate 2 2 Rate 3 3 Rate 4 4 Rate 1 +channel coding 5 Rate 2 + channel coding 6 Rate 3 + channel coding 7Rate 4 + channel coding

Optionally, only MCSs 0 to 3 may be specified. For a wake-up receiverhaving no channel coding capability, it is considered that a current MCScorresponds to Rate 1 to Rate 4; and for a wake-up receiver having achannel coding capability, it is considered that a current MCScorresponds to Rate 1+channel coding to Rate 4+channel coding.

Optionally, a rate in Table 1 to Table 3 may be replaced with an MCSscheme.

It may be understood that the data rate in the foregoing tables may bespecifically in a form of a variable symbol length, or in a form of avariable symbol length+a variable frequency modulation order and/or avariable phase modulation order and/or a variable amplitude modulationorder.

Optionally, in S121, the feedback information includes secondinformation used to indicate a power of the first WUP when the first WUParrives at the wake-up receiver. Correspondingly, S122 is specificallyas follows: The transmit end device determines the second data ratebased on the second information and a preset power threshold.

Alternatively, in S121, the feedback information includes thirdinformation used to indicate a signal-to-noise ratio of the first WUP atthe wake-up receiver. Correspondingly, S122 is specifically as follows:The transmit end device determines the second data rate based on thethird information and a preset signal-to-noise ratio threshold.

Alternatively, in S121, the feedback information includes fourthinformation used to indicate a packet error rate of the first WUP at thewake-up receiver. Correspondingly, S122 is specifically as follows: Thetransmit end device determines the second data rate based on the fourthinformation and a preset packet error rate threshold.

Optionally, in an embodiment, a specific implementation in which thereceive end device sends the feedback information to the transmit enddevice by using the main transceiver is as follows: The receive enddevice sends a medium access control (Medium Access Control, MAC) frameto the transmit end device by using the main transceiver, where the MACframe carries the feedback information.

Specifically, the MAC frame is a quality of service (Quality of Service,QoS) data (Data) frame. FIG. 7 shows a frame structure of a QoS dataframe according to an embodiment of this application. As shown in FIG.7, the QoS data frame includes a frame control (Frame Control) field, aduration/identifier (Duration/ID) field, an address (Address) 1 field,an address 2 field, an address 3 field, a sequence control (SequenceControl) field, an address 4 field, a quality of service control (QoSControl) field, a high throughput control (HT Control) field, a framebody (Frame Body) field, and a frame check sequence FCS field. The HTcontrol field carries the feedback information.

Alternatively, the MAC frame is a QoS null (Null) frame, and the QoSnull frame includes a high efficiency aggregated control (HighEfficiencyAggregated Control, HE-A-Control) field. FIG. 8 shows astructure of a high efficiency aggregated control field according to anembodiment of this application. As shown in FIG. 8, the HE-A-Controlfield includes an extremely high throughput field, a high efficiencyfield, and an aggregated control (Aggregated Control) field. Theaggregated control field includes a plurality of control (control 1 tocontrol N) fields and a padding (Padding) field. Each control fieldincludes a control identifier field and a control information (ControlInfo) field. The control information field includes a number of spatialflows (Number of Spatial Stream, NSS) field, an HE-MCS field, a wake-upreceiver field, a channel information field, and a reserved field. Thewake-up receiver field carries the feedback information.

In an actual communication process, a function of each control field isdetermined by changing a value indicated by the control identifierfield. For example, when the control identifier field indicates 2, itindicates that information in the control field is used for linkadaptation, and feedback of a channel quality indication (ChannelQuality Indication, CQI), an MCS, and the like. In addition, whether thefeedback information is applied to rate adjustment of the wake-upreceiver or link adaptation of a main radio is determined based on anindication of the wake-up receiver field. For example, if the wake-upreceiver field indicates “1”, it indicates that the feedback informationis applied to the rate adjustment of the wake-up receiver; or if thewake-up receiver field indicates “0”, it indicates that the feedbackinformation is applied to the link adaptation of the main radio.

Further, the control information field may further carry channelinformation, to indicate that the feedback information is informationused for which channel/resource block. Further, rate information on aplurality of channels/resource blocks may be fed back. A new controlidentifier field may be further added, and the new control identifierfield carries the feedback information.

Optionally, the MAC frame is a beamforming report (Beamforming Report).FIG. 9 is a structural diagram of a beamforming report according to anembodiment of this application. As shown in FIG. 9, the beamformingreport includes a frame control field, a high efficiency multiple-inputmultiple-output (Multiple Input Multiple Output, MIMO) control field, awake-up receiver rate feedback field, and a frame check sequence field.The wake-up receiver rate feedback field is used to carry the feedbackinformation. A reserved bit of the high efficiency MIMO control field isused to indicate that the beamforming report is used to carry thefeedback information.

It should be noted that the MAC frame in this embodiment of thisapplication is not limited to the several types of MAC frames listedabove, and may alternatively be another type of MAC frame, for example,a newly defined MAC frame in a standard, or a newly defined action noACK frame (an action frame that does not need an acknowledgment).

Optionally, in an embodiment, the transmit end device carries thefeedback information by using an information element (InformationElement). FIG. 10 is a structural diagram of an information elementaccording to an embodiment of this application. As shown in FIG. 10, theinformation element includes an element identifier (Element Identifier)field, a length (Length) field, an element identifier extension (ElementIdentifier Extension) field, and an information (Information) field. Theinformation field includes a wake-up receiver rate feedback field, andthe wake-up receiver rate feedback field carries the feedbackinformation. In an actual communication process, different elementidentifier fields may be used to indicate that the information fieldcarries different management information. The information element may becarried in a management frame. The management frame may be an action noACK frame, an ACK frame, or a beacon frame. However, this application isnot limited thereto.

In the foregoing embodiment, a form for feeding back the data rate byusing the feedback information may be separately indicating a data rateon each channel/resource block, or may be first indicating some commoninformation and then indicating information of each resource block.

Further, for downlink feedback, rates on a plurality of point-to-pointchannels between a station STA and an access point AP may be fed back;and rates on a plurality of channels between an AP and a plurality ofSTAs may be further fed back. In addition, the data rate may be carriedby using a multiple-STA block acknowledgement (Multiple-STA BlockAcknowledgement, M-BA) frame or a trigger (Trigger) frame.

For example, FIG. 11 shows a structure of an M-BA frame according to anembodiment of this application. As shown in FIG. 11, the M-BA frameincludes a frame control field, a duration (Duration) field, a receiveaddress (Receive Address, “RA” for short) field, and a transmit address(Transmit Address, TA) field, a BA control field, a BA informationfield, and an FCS field. The BA information field includes a repeatedper STA information (Per STA Info) field, a block acknowledgmentstarting sequence control (Block ACK Starting Sequence Control) field,and a block acknowledgment bitmap (Block ACK Bitmap) field. The per STAinformation field includes an association identifier (AssociationIdentifier, AID) field, an ACK/BA field, and a traffic identifier(Traffic Identifier, TID) value (Value) field. A special TID/AID valuemay be used to indicate that the block ACK starting sequence controlfield and the block ACK bitmap field are used to carry the data rate ofthe wake-up receiver.

FIG. 12 shows a structure of a trigger frame according to an embodimentof this application. As shown in FIG. 12, the trigger frame includes aframe control field, a trigger frame type field, a common field relatedto a trigger frame type, a common information field, astation-by-station information field, and an FCS field. The common fieldrelated to the trigger frame type is used to carry the data rate.Alternatively, as shown in FIG. 12, the station-by-station informationfield includes a wake-up receiver rate field that is used to carry thedata rate.

It should be noted that, the method in which the AP feeds back the datarate to a plurality of STAs is also applicable to a process in which theSTA feeds back a data rate to the AP. The method is not only applicableto a process in which the STA feeds back data rates for wake-up packetson a plurality of channels/resource blocks to one AP, and is alsoapplicable to a process in which the STA feeds back data rates forwake-up packets on a plurality of channels/resource blocks to aplurality of APs or STAs.

In this embodiment of this application, optionally, the transmit enddevice may indicate, to the receive end device, a data rate used whenthe transmit end device transmits the wake-up packet, so that thereceive end device receives and parses the received wake-up packet basedon the data rate. FIG. 13 is a schematic structural diagram of a wake-uppacket according to another embodiment of this application. As shown inFIG. 13, the wake-up packet includes a preamble field, a signaling(Signaling, SIG) field, and a data (payload) field. The preamble fieldis used by the receive end device to perform automatic gain control(Automatic Gain Control, ACG) and time synchronization. The signalingfield includes a rate indication field. The rate indication field isused to indicate the second data rate. The signaling field may furtherinclude a field used to carry other information used for parsing data.This is not limited in this application.

Further, after the wake-up receiver of the receive end device receivesthe wake-up packet, the data rate cannot be adjusted immediately. Asshown in FIG. 14, a redundancy field is added after the SIG field (afterthe rate indication field if the SIG field includes only the rateindication field), where the redundancy field may include N symbols, andN is a positive integer greater than or equal to 1, so that the wake-upreceiver adjusts the data rate.

Optionally, in an embodiment, M symbols of a fixed data rate (symbollength and/or MCS) may be placed after the SIG field, where a value of Mmay be 1, 2, or the like, so that the receive end device performschannel estimation based on the M symbols of the fixed data rate.

Optionally, in an embodiment, the receive end device may determine thesecond data rate based on a correspondence between a preamble mode and adata rate. For example, the correspondence between a preamble mode and adata rate may be preset. After determining a preamble mode, the receiveend device may determine a current data rate based on the determinedpreamble mode and the correspondence. For example, if the preamble modeis 10101010, it is considered that a data rate of a subsequent data partis a rate 1; or if the preamble mode is 110011001100, it is consideredthat a data rate of a subsequent data part is a rate 2. Alternatively,if an additional sequence is further included in the preamble fieldafter the field that carries the information used by the receive enddevice to perform time synchronization or AGC, the receive end devicemay determine the data rate based on the additional sequence. Forexample, if the preamble field is “time synchronization/AGC”codeword+sequence 1, the receive end device determines that the datarate is a rate 1; or if the preamble field is “timesynchronization/AGC+sequence 2”, the receive end device determines thatthe data rate is a rate 2.

Optionally, in an embodiment, the receive end device may determine thedata rate of the wake-up packet by using a data rate used by the maintransceiver. Specifically, a correspondence exists between a data rateof a wake-up packet and a data rate of a main transceiver. For example,if the main transceiver uses MCSs 0 to 2, a rate 1 is used for thewake-up packet; or if the main transceiver uses MCSs 3 to 5, a rate 2 isused for the wake-up packet.

Optionally, in an embodiment, the receive end device may determine thedata rate of the wake-up packet by using an operating frequency band ofthe main transceiver and/or an operating frequency band of the wake-upradio. For example, when the main transceiver and the wake-up receiverare on a same operating frequency band (both on 2.4 GHz or both on 5GHz), a rate 1 is used for the wake-up packet; when the main transceiverand the wake-up receiver are on different operating frequency bands (themain transceiver is on 2.4 GHz and the wake-up radio is on 5 GHz), arate 2 is used for the wake-up packet; or when the main transceiver andthe wake-up receiver are on different operating frequency bands (themain transceiver is on 5 GHz and the wake-up radio is on 2.4 GHz), arate 3 is used for the wake-up packet.

Optionally, in an embodiment, the receive end device may determine thedata rate by using a result of negotiation between the main transceiverand the transmit end device. For example, the receive end device maysend the QoS data frame, the QoS null frame, the beamforming report, orthe like to the transmit end device, to inform the transmit end deviceof the data rate expected by the receive end device. If the transmit enddevice confirms that the data transmission rate expected by the receiveend device can be used, the transmit end device sends an acknowledgmentframe to the receive end device. After receiving the acknowledgmentframe sent by the transmit end device, the receive end device considersthat a data rate subsequently used by the transmit end device totransmit the wake-up packet is the data rate that is expected by thereceive end device and that is previously fed back.

Optionally, in another embodiment, if the receive end device is the STAand the transmit end device is the AP, when the STA is associated withthe AP, the AP directly specifies, based on a distance between the STAand the AP, a data rate used when the AP transmits the wake-up packet tothe STA. The transmit end device may update the data rate by using aprimary channel of main radio between the transmit end device and themain transceiver in a data exchange process, for example, update thedata rate through interaction of an operation mode notification(Operation Mode Notification).

It should be noted that, in the foregoing solution in which the receiveend device is informed of the data rate by using a method in which theSIG field carries the information used to indicate the data rate, datarates used by the transmit end device to send the preamble field, theSIG field, and the data field in the wake-up packet to the receive enddevice may be different, and a more robust rate may be used for sendingthe preamble field and the SIG field.

In the foregoing other solutions for informing the receive end device ofthe data rate, the receive end device may parse the preamble field andthe SIG field by using a specific data rate, and parse data based on theagreed-on, negotiated, or calculated data rate in the foregoingsolutions. In this case, the transmit end device may send the preamblefield and the data field by using different data rates, and send thepreamble field by using a more robust data rate. Alternatively, thereceive end device may parse the entire wake-up packet based on theagreed-on or negotiated data rate in the foregoing solutions. In thiscase, the transmit end device sends the preamble field and the datafield by using a same data rate.

When the transmit end device sends the wake-up packet to the wake-upreceiver of the receive end device, the transmit end device needs toinform the receive end device whether the currently sent wake-up packetis sent to the wake-up receiver of the receive end device. In this case,the data field part in the structure of the wake-up packet shown in FIG.13 or FIG. 14 includes a MAC header field, where the MAC header fieldincludes an identifier information field, and the identifier informationfield is used to carry identifier information of a receive end device.The identifier information may be a MAC address, an AID, or a partial(Partial) AID. To avoid unnecessary overheads caused by excessiveinformation bits included in the identifier information field, aquantity of information bits included in the identifier informationfield may be positively correlated with a magnitude of the second datarate.

It is assumed that an identifier ID is an AID. In this case, a first bitof an AID of a receive end device needing a relatively low data rate isset to 1, and a first bit of an AID of another receive end deviceneeding a relatively high data rate is set to 0. It is assumed thatthere are n receive end devices needing a relatively low data rate, anaddress information field only needs to include 1+ceil(log₂(n)) bits todistinguish between the receive end devices, where ceil( ) is a round-upfunction. Alternatively, more generally, first s bits of an AID are usedto identify user groups with different data rates. For example, whens=2, 00 represents a user group with a maximum data rate, 01 representsa user group with a second largest data rate, 10 represents a user groupwith a third largest data rate, and 11 indicates a user group with aminimum data rate. A following bit combination is used to distinguisheach user group, specifically as shown in FIG. 15. In addition, if theforegoing method for indicating the data rate is combined, when thewake-up packet carries the AID shown in FIG. 15, first two bits may notbe transmitted.

Optionally, the MAC header field may further include a bit quantityindication field, and the bit quantity indication field is used to carryinformation indicating a quantity of information bits included in theidentifier information field. The bit quantity indication field mayindicate a specific quantity of information bits, or the bit quantityindication field may indicate a correspondence between a quantity ofinformation bits and a data rate.

Further, when an ID is allocated to a receive end device needing arelatively low data rate, continuous occurrence of a plurality ofsymbols with a symbol energy of 0 should be avoided as much as possible,to reduce transmission of redundant information.

In all the foregoing embodiments, when the transmit end device sends thesecond WUP to the wake-up receiver of the receive end device by usingthe second data rate, the transmit end device modulates an informationbit in the second WUP into a plurality of modulation symbols based onthe second data rate, where the plurality of modulation symbols includea first modulation symbol whose symbol energy is 0 and a secondmodulation symbol whose symbol energy is not 0; and then the transmitend device sends the plurality of modulation symbols to the wake-upreceiver of the receive end device.

Optionally, in an example, when the transmit end device sends aplurality of modulation symbols to the wake-up receiver of the receiveend device, one placeholder (ON) symbol may be inserted at an intervalof N modulation symbols to occupy a channel, so as to avoid thefollowing case: The channel is in an idle state for a long time, andconsequently, another receive end device preempts the channel, affectingtransmission of the wake-up packet. Herein, N may be a fixed value. Forexample, N may be 4. Alternatively, N may be a value determined based ona symbol length of the modulation symbol. For example, it is assumedthat the symbol length is x μs, and a communications system may accept amaximum time of y μs in which modulation symbols whose symbol energy is0 are continuously sent (y may be specified in a standard in advance, oragreed on when the AP is associated with the STA). In this case,N=floor(y/x). It is assumed that x=4 and y=25. In this case,N=floor(25/4)=6. Alternatively, N has a one-to-one correspondence with asymbol length. For example, it may be agreed that a symbol length of 2μs corresponds to N=12, a symbol length of 4 μs corresponds to N=6, anda symbol length of 8 μs corresponds to N=3.

Correspondingly, in a receiving process, each time the wake-up receiverof the receive end device receives N modulation symbols, the wake-upreceiver of the receive end device ignores a next symbol. If N changeswith the symbol length, the receive end device may learn of a currentsymbol length based on explicit or implicit indication of the transmitend device, and then determine N values based on the method forcalculating N or the one-to-one correspondence between N and a symbollength that are mentioned above.

Optionally, in another example, when the transmit end device sends aplurality of modulation symbols to the wake-up receiver of the receiveend device, one placeholder symbol may be inserted at an interval of Nfirst modulation symbols whose symbol energy is 0, where selection of Nis the same as the foregoing method. Details are not described hereinagain.

Correspondingly, each time the receive end device receives the N firstmodulation symbols whose symbol energy is 0, the receive end deviceignores a next symbol.

It should be noted that the placeholder symbol in the foregoing does notcarry an information bit, but a symbol energy of the placeholder symbolis not 0.

Optionally, the transmit end device may multiplex an OFDM transmitter togenerate a plurality of time domain symbols corresponding to theinformation bit in the second WUP. A method for generating a time domainsymbol whose symbol energy is not 0 is: generating, by the transmit enddevice, a time domain sequence s_pre, where values in s_pre have a sameamplitude; performing fast Fourier transform (Fast Fourier Transform,FFT) on s_pre to obtain a frequency domain sequence s; filling s into asubcarrier on an operating frequency band of the wake-up receiver; andthen performing IFFT on s to transform s into time domain and form atime domain symbol. A length of the time domain sequence s_pre may bedetermined based on a ratio of an operating bandwidth of the wake-upreceiver to a subcarrier width. For example, if the operating bandwidthof the wake-up receiver is 4 M and the subcarrier width is 312.5 kHz,the length of s_pre is 13; or if the operating bandwidth of the wake-upreceiver is 4 M and the subcarrier width is 78.125 kHz, the length ofs_pre is 52. Optionally, for ease of operation of the FFT transform, thelength of s_pre may be specified as an even number.

Alternatively, the transmit end device directly determines a frequencydomain sequence s, where a distance between two neighboring non-zerovalues in the sequence s is n Os, and n may be 1, 2, 3, or 4. Forexample, when n is 1, s may be represented as: s=[s₁, 0, s₂, 0, s₃, 0,s₄, . . . ].

In this embodiment of this application, optionally, as shown in FIG. 16,the transmit end device may send wake-up packets to different receiveend devices by using different frequencies in one transmission. Whengenerating time domain symbols corresponding to an information bit in awake-up packet of each receive end device, the transmit end device mayfirst multiply s of the wake-up packet of each receive end device bydifferent twiddle factors. For example, the twiddle factor may beselected from [1, −1, j, −j], where 1 indicates no twiddling, −1indicates twiddling by 180°, j indicates twiddling by 90°, and −jindicates twiddling by −90°. In a specific example, when four wake-uppackets are simultaneously transmitted, twiddle factors corresponding tos sequences of the wake-up packets 1 to 4 are [1, −1, −1, −1], to bespecific, s is filled into a subcarrier corresponding to the wake-uppacket 1, and −s is filled into subcarriers corresponding to the wake-uppacket 2 to the wake-up packet 4.

Alternatively, the transmit end device may generate a full bandwidthfilling sequence s. When there is a wake-up packet on a correspondingfrequency needing to be sent, a value at a position corresponding to sis filled into a corresponding subcarrier. For example, s uses an 1-stfsequence:

S _(−26,26)=√{square root over(1/2)}{0,0,1+j,0,0,0,−1−j,0,0,0,−1−j,0,0,0,−1−j,0,0,0,1+j,0,0,0,0,0,0,0,−1−j,0,0,0,−1−j,0,0,0,1+j,0,0,0,1+j,0,0,0,1+j,0,0,0,1+j,0,0}

When only the wake-up packet 1 needs to be transmitted, the value at theposition corresponding to the full bandwidth filling sequence s isfilled into the corresponding subcarrier. For example, a “0, 0, 1+j, 0,0, 0, −1−j, 0, 0, 0, 1+j, 0, 0” sequence is filled into 13 subcarrierscorresponding to 4 M.

With reference to FIG. 4 to FIG. 16, the foregoing describes in detailthe method for transmitting a wake-up packet in a communications systemaccording to the embodiments of this application. With reference to FIG.17, the following describes in detail a transmit end device according toan embodiment of this application.

FIG. 17 shows a transmit end device 10 in a communications systemaccording to an embodiment of this application. The communicationssystem includes the transmit end device and a receive end device, andthe receive end device includes a wake-up receive module and a maintransceiver module. As shown in FIG. 17, the transmit end device 10includes:

a transceiver module 11, configured to send a first wake-up packet WUPto the wake-up receive module by using a first data rate; and

a determining module 12, configured to determine a second data rate,where

the transceiver module 11 is further configured to send a second WUP tothe wake-up receive module by using the second data rate.

Therefore, the transmit end device according to this embodiment of thisapplication can send wake-up packets to the receive end device by usingdifferent data rates, so that the transmit end device can determine,based on a specific transmission condition in a communication process, aproper data rate for sending a wake-up packet, thereby improvingefficiency of transmitting the wake-up packet.

In this embodiment of this application, optionally, in the aspect ofsending the first wake-up packet to the wake-up receive module by usingthe first data rate, the transceiver module 11 is specificallyconfigured to send the first WUP to the wake-up receive module by usinga first symbol rate;

in the aspect of determining the second data rate, the determiningmodule 12 is specifically configured to determine a second symbol rate;and

in the aspect of sending the second WUP to the wake-up receive module byusing the second data rate, the transceiver module 11 is specificallyconfigured to send the second WUP to the wake-up receive module by usingthe second symbol rate.

In this embodiment of this application, optionally, in the aspect ofsending the first wake-up packet WUP to the wake-up receive module byusing the first data rate, the transceiver module 11 is specificallyconfigured to send the first WUP to the wake-up receive module by usinga first modulation and coding scheme;

in the aspect of determining the second data rate, the determiningmodule 12 is specifically configured to determine a second modulationand coding scheme; and

in the aspect of sending the second WUP to the wake-up receive module byusing the second data rate, the transceiver module 11 is specificallyconfigured to send the second WUP to the wake-up receive module by usingthe second modulation and coding scheme.

In this embodiment of this application, optionally, in the aspect ofdetermining the second data rate, the determining module 12 isspecifically configured to determine the second data rate based on adata rate used when the transmit end device 10 sends data to the maintransceiver module.

In this embodiment of this application, optionally, in the aspect ofdetermining the second data rate, the determining module 12 isspecifically configured to determine the second data rate based on anoperating frequency band of the main transceiver module and/or anoperating frequency band of the wake-up receive module.

In this embodiment of this application, optionally, in the aspect ofdetermining the second data rate, the determining module 12 isspecifically configured to determine a symbol length corresponding tothe second data rate based on a multipath delay spread.

In this embodiment of this application, optionally, in the aspect ofdetermining the second data rate, the transceiver module 11 isconfigured to receive feedback information sent by the receive enddevice by using the main transceiver module; and

the determining module 12 is configured to determine the second datarate based on the feedback information.

In this embodiment of this application, optionally, the feedbackinformation includes first information used to indicate asignal-to-noise ratio on an operating frequency of the main transceivermodule and/or the wake-up receive module; and

in the aspect of determining the second data rate based on the feedbackinformation, the determining module 12 is specifically configured todetermine the second data rate based on the first information and acorrespondence between a signal-to-noise ratio and a data rate.

In this embodiment of this application, optionally, the feedbackinformation includes second information used to indicate a power of thefirst WUP when the first WUP arrives at the wake-up receive module, andin the aspect of determining the second data rate based on the feedbackinformation, the determining module 12 is configured to determine thesecond data rate based on the second information and a preset powerthreshold; or

the feedback information includes third information used to indicate asignal-to-noise ratio of the first WUP at the wake-up receive module,and in the aspect of determining the second data rate based on thefeedback information, the determining module 12 is configured todetermine the second data rate based on the third information and apreset signal-to-noise ratio threshold; or

the feedback information includes fourth information used to indicate apacket error rate of the first WUP at the wake-up receive module, and inthe aspect of determining the second data rate based on the feedbackinformation, the determining module 12 is configured to determine thesecond data rate based on the fourth information and a preset packeterror rate threshold.

In this embodiment of this application, optionally, in the aspect ofreceiving the feedback information sent by the receive end device byusing the main transceiver module, the transceiver module 11 isspecifically configured to receive a medium access control MAC framesent by the receive end device by using the main transceiver module,where the MAC frame carries the feedback information.

In this embodiment of this application, optionally, in the aspect ofreceiving the medium access control MAC frame sent by the receive enddevice by using the main transceiver module, the transceiver module 11is specifically configured to: receive a quality of service QoS dataframe sent by the receive end device by using the main transceivermodule, where the QoS data frame includes a high throughput controlfield, and the high throughput control field carries the feedbackinformation; or receive a QoS null frame sent by the receive end deviceby using the main transceiver module, where the QoS null frame includesa high efficiency aggregated control field, and the high efficiencyaggregated control field carries the feedback information; or receive abeamforming report sent by the receive end device by using the maintransceiver module, where the beamforming report includes a feedbackfield, and the feedback field carries the feedback information.

In this embodiment of this application, optionally, in the aspect ofsending the second WUP to the wake-up receive module by using the seconddata rate, the transceiver module 11 is specifically configured to:modulate an information bit in the second WUP into a plurality ofmodulation symbols based on the second data rate, where the plurality ofmodulation symbols include a first modulation symbol whose symbol energyis 0 and a second modulation symbol whose symbol energy is not 0; andsend the plurality of modulation symbols to the wake-up receive module.

In this embodiment of this application, optionally, in the aspect ofsending the plurality of modulation symbols to the wake-up receivemodule, the transceiver module 11 is specifically configured to: sendthe plurality of modulation symbols to the wake-up receive module in amanner of sending one placeholder symbol to the wake-up receive moduleeach time the transceiver module sends a first preset quantity ofmodulation symbols to the wake-up receive module, where the placeholdersymbol does not carry an information bit, and a symbol energy of theplaceholder symbol is not 0; or send the plurality of modulation symbolsto the wake-up receive module in a manner of sending one placeholdersymbol to the wake-up receive module each time the transceiver modulesends a second preset quantity of first modulation symbols to thewake-up receive module, where the placeholder symbol does not carry aninformation bit, and a symbol energy of the placeholder symbol is not 0.

In this embodiment of this application, optionally, the second WUPincludes a signaling field and a data field that are arranged in asending time sequence, and the signaling field carries indicationinformation used to indicate the second data rate.

In this embodiment of this application, optionally, the second WUPfurther includes a redundancy field, and a sending time of theredundancy field is after a sending time of the signaling field andbefore a sending time of the data field.

In this embodiment of this application, optionally, the second WUPincludes a preamble field and a data field that are in a sending timesequence, so that the receive end device determines the second data ratebased on a preamble mode corresponding to the preamble field and apreset correspondence, where the preset correspondence includes acorrespondence between a preamble mode and a data rate.

In this embodiment of this application, optionally, the second WUPincludes a MAC header field, the MAC header field includes an identifierinformation field, the identifier information field is used to carryidentifier information of the receive end device, and the determiningmodule 12 is further configured to determine, based on the second datarate, a quantity of information bits included in the identifierinformation field, where the quantity of information bits included inthe identifier information field is positively correlated with amagnitude of the second data rate.

It should be understood that the transmit end device 10 according tothis embodiment of this application may correspondingly perform themethod 100 for transmitting a wake-up packet in a communications systemin the embodiments of this application, and the foregoing and otheroperations and/or functions of each module in the transmit end device 10are respectively used to implement corresponding procedures executed bythe transmit end device in the method 100. For brevity, details are notdescribed herein again.

FIG. 18 shows a receive end device 20 in a communications systemaccording to an embodiment of this application. The communicationssystem includes a transmit end device and the receive end device. Asshown in FIG. 18, the receive end device 20 includes a wake-up receivemodule 21, a main receive module 22, and a determining module 23.

The wake-up receive module 21 is configured to receive a first wake-uppacket WUP sent by the transmit end device by using a first data rate.

The wake-up receive module 21 is further configured to receive a secondWUP sent by the transmit end device by using a second data rate.

The determining module 23 is configured to determine the second datarate.

The determining module 23 is further configured to parse the second WUPbased on the second data rate.

Therefore, the receive end device in a communications system accordingto this embodiment of this application receives wake-up packets sent bythe transmit end device by using different data rates, and the transmitend device can determine, based on a specific transmission condition ina communication process, a proper data rate for sending a wake-uppacket, thereby improving efficiency of transmitting the wake-up packet.

In this embodiment of this application, optionally, in the aspect ofreceiving the first wake-up packet WUP sent by the transmit end deviceby using the first data rate, the wake-up receive module 21 isspecifically configured to receive the first WUP sent by the transmitend device by using a first symbol rate;

in the aspect of receiving the second WUP sent by the transmit enddevice by using the second data rate, the wake-up receive module 21 isconfigured to receive the second WUP sent by the transmit end device byusing a second symbol rate; in the aspect of determining the second datarate, the determining module 23 is specifically configured to determinethe second symbol rate; and in the aspect of parsing the second WUPbased on the second data rate, the determining module 23 is specificallyconfigured to parse the second WUP based on the second symbol rate.

In this embodiment of this application, optionally, in the aspect ofreceiving the first wake-up packet WUP sent by the transmit end deviceby using the first data rate, the wake-up receive module 21 isspecifically configured to receive the first WUP sent by the transmitend device by using a first modulation and coding scheme; in the aspectof receiving the second WUP sent by the transmit end device by using thesecond data rate, the wake-up receive module 21 is specificallyconfigured to receive the second WUP sent by the transmit end device byusing a second modulation and coding scheme; in the aspect ofdetermining the second data rate, the determining module 23 isspecifically configured to determine the second modulation and codingscheme; and in the aspect of parsing the second WUP based on the seconddata rate, the determining module 23 is specifically configured to parsethe second WUP based on the second modulation and coding scheme.

In this embodiment of this application, optionally, the main receivemodule 22 is specifically configured to send feedback information to thetransmit end device, so that the transmit end device determines thesecond data rate based on the feedback information.

In this embodiment of this application, optionally, the feedbackinformation includes first information used to indicate asignal-to-noise ratio on an operating frequency of the main transceivermodule and/or the wake-up receive module, so that the transmit enddevice determines the second data rate based on the first informationand a correspondence between a signal-to-noise ratio and a data rate.

In this embodiment of this application, optionally, the feedbackinformation includes second information used to indicate a power of thefirst WUP when the first WUP arrives at the wake-up receive module, sothat the transmit end device determines the second data rate based onthe second information and a preset power threshold; or the feedbackinformation includes third information used to indicate asignal-to-noise ratio of the first WUP at the wake-up receive module, sothat the transmit end device determines the second data rate based onthe third information and a preset signal-to-noise ratio threshold; orthe feedback information includes fourth information used to indicate apacket error rate of the first WUP at the wake-up receive module, sothat the transmit end device determines the second data rate based onthe fourth information and a preset packet error rate threshold.

In this embodiment of this application, optionally, in the aspect ofsending the feedback information to the transmit end device, the maintransceiver module 22 is configured to send a medium access control MACframe to the transmit end device, where the MAC frame carries thefeedback information.

In this embodiment of this application, optionally, in the aspect ofsending the medium access control MAC frame to the transmit end device,the main transceiver module 22 is specifically configured to: send aquality of service QoS data frame to the transmit end device, where theQoS data frame includes a high throughput control field, and the highthroughput control field carries the feedback information; or send a QoSnull frame to the transmit end device, where the QoS null frame includesa high efficiency aggregated control field, and the high efficiencyaggregated control field carries the feedback information; or send abeamforming report to the transmit end device, where the beamformingreport includes a feedback field, and the feedback field carries thefeedback information.

In this embodiment of this application, optionally, in the aspect ofreceiving the second WUP sent by the transmit end device by using thesecond data rate, the wake-up receive module 21 is specificallyconfigured to receive a plurality of modulation symbols sent by thetransmit end device, where the plurality of modulation symbols areobtained by the transmit end device by modulating an information bit inthe second WUP based on the second data rate, and the plurality ofmodulation symbols include a first modulation symbol whose symbol energyis 0 and a second modulation symbol whose symbol energy is not 0.

In this embodiment of this application, optionally, the plurality ofmodulation symbols are sent by the transmit end device in a manner ofsending one placeholder symbol to the wake-up receive module 21 eachtime the transmit end device sends a first preset quantity of modulationsymbols to the wake-up receive module 21, the placeholder symbol doesnot carry an information bit, and a symbol energy of the placeholdersymbol is not 0; and

in the aspect of receiving the plurality of modulation symbols sent bythe transmit end device, the wake-up receive module 21 is specificallyconfigured to receive the plurality of modulation symbols in a manner ofignoring the placeholder symbol each time the wake-up receive module 21receives the first preset quantity of modulation symbols.

In this embodiment of this application, optionally, the plurality ofmodulation symbols are sent by the transmit end device in a manner ofsending one placeholder symbol to the wake-up receive module 21 eachtime the transmit end device sends a second preset quantity of secondmodulation symbols to the wake-up receive module 21, the placeholdersymbol does not carry an information bit, and a symbol energy of theplaceholder symbol is not 0; and

in the aspect of receiving the plurality of modulation symbols sent bythe transmit end device, the wake-up receive module 21 is specificallyconfigured to receive the plurality of modulation symbols in a manner ofignoring the placeholder symbol each time the wake-up receive module 21receives the second preset quantity of second modulation symbols.

In this embodiment of this application, optionally, the second WUPincludes a signaling field and a data field that are arranged in asending time sequence, and the signaling field carries indicationinformation used to indicate the second data rate; and in the aspect ofdetermining the second data rate, the determining module 23 isspecifically configured to determine the second data rate based on theindication information.

In this embodiment of this application, optionally, the second WUPfurther includes a redundancy field, and a sending time of theredundancy field is after a sending time of the signaling field andbefore a sending time of the data field.

In this embodiment of this application, optionally, the second WUPincludes a preamble field and a data field that are in a sending timesequence; and

in the aspect of determining the second data rate, the determiningmodule 23 is specifically configured to determine the second data ratebased on a preamble mode corresponding to the preamble field and apreset correspondence, where the preset correspondence includes acorrespondence between a preamble mode and a data rate.

In this embodiment of this application, optionally, the second WUPincludes a MAC header field, the MAC header field includes an identifierinformation field, the identifier information field is used to carryidentifier information of the receive end device, and a quantity ofinformation bits included in the identifier information field ispositively correlated with a magnitude of the second data rate.

It should be understood that the receive end device 20 according to thisembodiment of this application may correspondingly perform the method100 for transmitting a wake-up packet in a communications system in theembodiments of this application, and the foregoing and other operationsand/or functions of each module in the receive end device 20 arerespectively used to implement corresponding procedures executed by thereceive end device in the method 100. For brevity, details are notdescribed herein again.

FIG. 19 is a schematic structural diagram of a transmit end device 100in a communications system according to another embodiment of thisapplication. The communications system includes the transmit end deviceand a receive end device, and the receive end device includes a wake-upreceiver and a main transceiver. The transmit end device in FIG. 19 mayexecute a procedure executed by the transmit end device in eachprocedure in the method 100. The transmit end device 100 in FIG. 19includes a transceiver 110, a processor 120, and a memory 130. Theprocessor 120 controls an operation of the transmit end device 100, andmay be configured to process a signal. The memory 130 may include aread-only memory and a random access memory, and provide an instructionand data for the processor 120. Components of the transmit end device100 are coupled together by using a bus system 140. In addition to adata bus, the bus system 140 further includes a power bus, a controlbus, and a status signal bus. However, for clear description, varioustypes of buses in the figure are marked as the bus system 140.

Specifically, the transceiver 110 is configured to send a first wake-uppacket WUP to the wake-up receive module by using a first data rate; theprocessor 120 is configured to determine a second data rate; and thetransceiver 110 is further configured to send a second WUP to thewake-up receive module by using the second data rate.

It should be understood that in this embodiment of this application, theprocessor 120 may be a central processing unit (Central Processing Unit,CPU), or the processor 120 may be another general-purpose processor, adigital signal processor (DSP), an application-specific integratedcircuit (ASIC), a field programmable gate array (FPGA) or anotherprogrammable logic device, a discrete gate or a transistor logic device,a discrete hardware component, or the like. The general-purposeprocessor may be a microprocessor, or the processor may be anyconventional processor or the like.

The memory 130 may include a read-only memory and a random accessmemory, and provide an instruction and data for the processor 120. Apart of the memory 130 may further include a non-volatile random accessmemory. For example, the memory 130 may further store information of adevice type.

In addition to a data bus, the bus system 140 may further include apower bus, a control bus, a status signal bus, and the like. However,for clear description, various types of buses in the figure are markedas the bus system 140.

In an implementation process, steps in the foregoing methods can beimplemented by using a hardware integrated logical circuit in theprocessor 120, or by using instructions in a form of software. The stepsof the methods disclosed with reference to the embodiments of thisapplication may be directly performed by a hardware processor, or may beperformed by using a combination of hardware in the processor and asoftware module. A software module may be located in a mature storagemedium in the art, such as a random access memory, a flash memory, aread-only memory, a programmable read-only memory, an electricallyerasable programmable memory, or a register. The storage medium islocated in the memory 130, and a processor 120 reads information in thememory 130 and completes the steps in the foregoing methods incombination with hardware of the processor. To avoid repetition, detailsare not described herein again.

Optionally, in an embodiment, in the aspect of sending the first wake-uppacket to the wake-up receiver by using the first data rate, thetransceiver 110 is specifically configured to send the first WUP to thewake-up receiver by using a first symbol rate;

in the aspect of determining the second data rate, the processor 120 isspecifically configured to determine a second symbol rate; and

in the aspect of sending the second WUP to the wake-up receiver by usingthe second data rate, the transceiver 110 is specifically configured tosend the second WUP to the wake-up receiver by using the second symbolrate.

Optionally, in an embodiment, in the aspect of sending the first wake-uppacket WUP to the wake-up receiver by using the first data rate, thetransceiver 110 is specifically configured to send the first WUP to thewake-up receiver by using a first modulation and coding scheme;

in the aspect of determining the second data rate, the processor 120 isspecifically configured to determine a second modulation and codingscheme; and

in the aspect of sending the second WUP to the wake-up receiver by usingthe second data rate, the transceiver 110 is specifically configured tosend the second WUP to the wake-up receiver by using the secondmodulation and coding scheme.

Optionally, in an embodiment, in the aspect of determining the seconddata rate, the processor 120 is specifically configured to determine thesecond data rate based on a data rate used when the transmit end device100 sends data to the main transceiver.

Optionally, in an embodiment, in the aspect of determining the seconddata rate, the processor 120 is specifically configured to determine thesecond data rate based on an operating frequency band of the maintransceiver and/or the wake-up receiver.

Optionally, in an embodiment, in the aspect of determining the seconddata rate, the processor 120 is specifically configured to determine asymbol length corresponding to the second data rate based on a multipathdelay spread.

Optionally, in an embodiment, in the aspect of determining the seconddata rate, the transceiver 110 is configured to receive feedbackinformation sent by the receive end device by using the maintransceiver; and

the processor 120 is configured to determine the second data rate basedon the feedback information.

Optionally, in an embodiment, the feedback information includes firstinformation used to indicate a signal-to-noise ratio on an operatingfrequency of the main transceiver and/or the wake-up receiver; and

in the aspect of determining the second data rate based on the feedbackinformation, the processor 120 is specifically configured to determinethe second data rate based on the first information and a correspondencebetween a signal-to-noise ratio and a data rate.

Optionally, in an embodiment, the feedback information includes secondinformation used to indicate a power of the first WUP when the first WUParrives at the wake-up receiver, and in the aspect of determining thesecond data rate based on the feedback information, the processor 120 isconfigured to determine the second data rate based on the secondinformation and a preset power threshold; or

the feedback information includes third information used to indicate asignal-to-noise ratio of the first WUP at the wake-up receiver, and inthe aspect of determining the second data rate based on the feedbackinformation, the processor 120 is configured to determine the seconddata rate based on the third information and a preset signal-to-noiseratio threshold; or

the feedback information includes fourth information used to indicate apacket error rate of the first WUP at the wake-up receiver, and in theaspect of determining the second data rate based on the feedbackinformation, the processor 120 is configured to determine the seconddata rate based on the fourth information and a preset packet error ratethreshold.

Optionally, in an embodiment, in the aspect of receiving the feedbackinformation sent by the receive end device by using the maintransceiver, the transceiver 110 is specifically configured to receive amedium access control MAC frame sent by the receive end device by usingthe main transceiver, where the MAC frame carries the feedbackinformation.

Optionally, in an embodiment, in the aspect of receiving the mediumaccess control MAC frame sent by the receive end device by using themain transceiver, the transceiver 110 is specifically configured to:receive a quality of service QoS data frame sent by the receive enddevice by using the main transceiver, where the QoS data frame includesa high throughput control field, and the high throughput control fieldcarries the feedback information; or receive a QoS null frame sent bythe receive end device by using the main transceiver, where the QoS nullframe includes a high efficiency aggregated control field, and the highefficiency aggregated control field carries the feedback information; orreceive a beamforming report sent by the receive end device by using themain transceiver, where the beamforming report includes a feedbackfield, and the feedback field carries the feedback information.

Optionally, in an embodiment, in the aspect of sending the second WUP tothe wake-up receiver by using the second data rate, the transceiver 110is specifically configured to: modulate an information bit in the secondWUP into a plurality of modulation symbols based on the second datarate, where the plurality of modulation symbols include a firstmodulation symbol whose symbol energy is 0 and a second modulationsymbol whose symbol energy is not 0; and send the plurality ofmodulation symbols to the wake-up receive module.

Optionally, in an embodiment, in the aspect of sending the plurality ofmodulation symbols to the wake-up receiver, the transceiver 110 isspecifically configured to: send the plurality of modulation symbols tothe wake-up receiver in a manner of sending one placeholder symbol tothe wake-up receiver each time the transceiver 110 sends a first presetquantity of modulation symbols to the wake-up receiver, where theplaceholder symbol does not carry an information bit, and a symbolenergy of the placeholder symbol is not 0; or send the plurality ofmodulation symbols to the wake-up receiver in a manner of sending oneplaceholder symbol to the wake-up receiver each time the transceiver 110sends a second preset quantity of first modulation symbols to thewake-up receiver, where the placeholder symbol does not carry aninformation bit, and a symbol energy of the placeholder symbol is not 0.

Optionally, in an embodiment, the second WUP includes a signaling fieldand a data field that are arranged in a sending time sequence, and thesignaling field carries indication information used to indicate thesecond data rate.

Optionally, in an embodiment, the second WUP further includes aredundancy field, and a sending time of the redundancy field is after asending time of the signaling field and before a sending time of thedata field.

Optionally, in an embodiment, the second WUP includes a preamble fieldand a data field that are in a sending time sequence, so that thereceive end device determines the second data rate based on a preamblemode corresponding to the preamble field and a preset correspondence,where the preset correspondence includes a correspondence between apreamble mode and a data rate.

Optionally, in an embodiment, the second WUP includes a MAC headerfield, the MAC header field includes an identifier information field,the identifier information field is used to carry identifier informationof the receive end device, and the processor 120 is further configuredto determine, based on the second data rate, a quantity of informationbits included in the identifier information field, where the quantity ofinformation bits included in the identifier information field ispositively correlated with a magnitude of the second data rate.

It should be understood that the transmit end device 100 according tothis embodiment of this application may correspond to the transmit enddevice 10 in the embodiments of this application, and may correspond toa corresponding entity for executing the method for transmitting awake-up packet in a communications system according to the embodimentsof this application, and the foregoing and other operations and/orfunctions of each module in the transmit end device 100 are respectivelyused to implement corresponding procedures in the method 100. Forbrevity, details are not described herein again.

Therefore, the transmit end device according to this embodiment of thisapplication can send wake-up packets to the receive end device by usingdifferent data rates, so that the transmit end device can determine,based on a specific transmission condition in a communication process, aproper data rate for sending a wake-up packet, thereby improvingefficiency of transmitting the wake-up packet.

FIG. 20 is a schematic structural diagram of a receive end device 200 ina communications system according to another embodiment of thisapplication. The communications system includes a transmit end deviceand the receive end device. The receive end device in FIG. 20 mayexecute a procedure executed by the receive end device in each procedurein the method 100. The receive end device 200 in FIG. 20 includes awake-up receiver 210, a main transceiver 220, a processor 230, and amemory 240. The processor 230 controls an operation of the receive enddevice 200, and may be configured to process a signal. The memory 240may include a read-only memory and a random access memory, and providean instruction and data for the processor 230. Components of the receiveend device 200 are coupled together by using a bus system 250. Inaddition to a data bus, the bus system 250 further includes a power bus,a control bus, and a status signal bus. However, for clear description,various types of buses in the figure are marked as the bus system 250.

Specifically, the wake-up receiver 210 is configured to receive a firstwake-up packet WUP sent by the transmit end device by using a first datarate; the wake-up receiver 210 is further configured to receive a secondWUP sent by the transmit end device by using a second data rate; theprocessor 230 is configured to determine the second data rate; and theprocessor 230 is further configured to parse the second WUP based on thesecond data rate.

It should be understood that in this embodiment of this application, theprocessor 230 may be a central processing unit (Central Processing Unit,CPU), or the processor 230 may be another general-purpose processor, adigital signal processor (DSP), an application-specific integratedcircuit (ASIC), a field programmable gate array (FPGA) or anotherprogrammable logic device, a discrete gate or a transistor logic device,a discrete hardware component, or the like. The general-purposeprocessor may be a microprocessor, or the processor may be anyconventional processor or the like.

The memory 240 may include a read-only memory and a random accessmemory, and provide an instruction and data for the processor 230. Apart of the memory 240 may further include a non-volatile random accessmemory. For example, the memory 240 may further store information of adevice type.

In addition to a data bus, the bus system 250 may further include apower bus, a control bus, a status signal bus, and the like. However,for clear description, various types of buses in the figure are markedas the bus system 250.

In an implementation process, steps in the foregoing methods can beimplemented by using a hardware integrated logical circuit in theprocessor 230, or by using instructions in a form of software. The stepsof the methods disclosed with reference to the embodiments of thisapplication may be directly performed by a hardware processor, or may beperformed by using a combination of hardware in the processor and asoftware module. A software module may be located in a mature storagemedium in the art, such as a random access memory, a flash memory, aread-only memory, a programmable read-only memory, an electricallyerasable programmable memory, or a register. The storage medium islocated in the memory 240, and a processor 230 reads information in thememory 240 and completes the steps in the foregoing methods incombination with hardware of the processor. To avoid repetition, detailsare not described herein again.

Optionally, in an embodiment, in the aspect of receiving the firstwake-up packet WUP sent by the transmit end device by using the firstdata rate, the wake-up receiver 210 is specifically configured toreceive the first WUP sent by the transmit end device by using a firstsymbol rate;

in the aspect of receiving the second WUP sent by the transmit enddevice by using the second data rate, the wake-up receiver 210 isconfigured to receive the second WUP sent by the transmit end device byusing a second symbol rate; in the aspect of determining the second datarate, the processor 230 is specifically configured to determine thesecond symbol rate; and in the aspect of parsing the second WUP based onthe second data rate, the processor 230 is specifically configured toparse the second WUP based on the second symbol rate.

Optionally, in an embodiment, in the aspect of receiving the firstwake-up packet WUP sent by the transmit end device by using the firstdata rate, the wake-up receiver 210 is specifically configured toreceive the first WUP sent by the transmit end device by using a firstmodulation and coding scheme; in the aspect of receiving the second WUPsent by the transmit end device by using the second data rate, thewake-up receiver 210 is specifically configured to receive the secondWUP sent by the transmit end device by using the second modulation andcoding scheme; in the aspect of determining the second data rate, theprocessor 230 is specifically configured to determine the secondmodulation and coding scheme; and in the aspect of parsing the secondWUP based on the second data rate, the processor 230 is specificallyconfigured to parse the second WUP based on the second modulation andcoding scheme.

Optionally, in an embodiment, the main transceiver 220 is specificallyconfigured to send feedback information to the transmit end device, sothat the transmit end device determines the second data rate based onthe feedback information.

Optionally, in an embodiment, the feedback information includes firstinformation used to indicate a signal-to-noise ratio on an operatingfrequency of the main transceiver 220 and/or the wake-up receiver 210,so that the transmit end device determines the second data rate based onthe first information and a correspondence between a signal-to-noiseratio and a data rate.

Optionally, in an embodiment, the feedback information includes secondinformation used to indicate a power of the first WUP when the first WUParrives at the wake-up receiver, so that the transmit end devicedetermines the second data rate based on the second information and apreset power threshold; or the feedback information includes thirdinformation used to indicate a signal-to-noise ratio of the first WUP atthe wake-up receiver, so that the transmit end device determines thesecond data rate based on the third information and a presetsignal-to-noise ratio threshold; or the feedback information includesfourth information used to indicate a packet error rate of the first WUPat the wake-up receiver, so that the transmit end device determines thesecond data rate based on the fourth information and a preset packeterror rate threshold.

Optionally, in an embodiment, in the aspect of sending the feedbackinformation to the transmit end device, the main transceiver 220 isconfigured to send a medium access control MAC frame to the transmit enddevice, where the MAC frame carries the feedback information.

Optionally, in an embodiment, in the aspect of sending the medium accesscontrol MAC frame to the transmit end device, the main transceiver 220is specifically configured to: send a quality of service QoS data frameto the transmit end device, where the QoS data frame includes a highthroughput control field, and the high throughput control field carriesthe feedback information; or send a QoS null frame to the transmit enddevice, where the QoS null frame includes a high efficiency aggregatedcontrol field, and the high efficiency aggregated control field carriesthe feedback information; or send a beamforming report to the transmitend device, where the beamforming report includes a feedback field, andthe feedback field carries the feedback information.

Optionally, in an embodiment, in the aspect of receiving the second WUPsent by the transmit end device by using the second data rate, thewake-up receiver 210 is specifically configured to receive a pluralityof modulation symbols sent by the transmit end device, where theplurality of modulation symbols are obtained by the transmit end deviceby modulating an information bit in the second WUP based on the seconddata rate, and the plurality of modulation symbols include a firstmodulation symbol whose symbol energy is 0 and a second modulationsymbol whose symbol energy is not 0.

Optionally, in an embodiment, the plurality of modulation symbols aresent by the transmit end device in a manner of sending one placeholdersymbol to the wake-up receiver 210 each time the transmit end devicesends a first preset quantity of modulation symbols to the wake-upreceiver 210, the placeholder symbol does not carry an information bit,and a symbol energy of the placeholder symbol is not 0; and

in the aspect of receiving the plurality of modulation symbols sent bythe transmit end device, the wake-up receiver 210 is specificallyconfigured to receive the plurality of modulation symbols in a manner ofignoring the placeholder symbol each time the wake-up receiver 210receives the first preset quantity of modulation symbols.

Optionally, in an embodiment, the plurality of modulation symbols aresent by the transmit end device in a manner of sending one placeholdersymbol to the wake-up receiver 210 each time the transmit end devicesends a second preset quantity of second modulation symbols to thewake-up receiver 210, the placeholder symbol does not carry aninformation bit, and a symbol energy of the placeholder symbol is not 0;and

in the aspect of receiving the plurality of modulation symbols sent bythe transmit end device, the wake-up receiver 210 is specificallyconfigured to receive the plurality of modulation symbols in a manner ofignoring the placeholder symbol each time the wake-up receiver 210receives the second preset quantity of second modulation symbols.

Optionally, in an embodiment, the second WUP includes a signaling fieldand a data field that are arranged in a sending time sequence, and thesignaling field carries indication information used to indicate thesecond data rate; and in the aspect of determining the second data rate,the processor 230 is specifically configured to determine the seconddata rate based on the indication information.

Optionally, in an embodiment, the second WUP further includes aredundancy field, and a sending time of the redundancy field is after asending time of the signaling field and before a sending time of thedata field.

Optionally, in an embodiment, the second WUP includes a preamble fieldand a data field that are in a sending time sequence; and

in the aspect of determining the second data rate, the processor 230 isspecifically configured to determine the second data rate based on apreamble mode corresponding to the preamble field and a presetcorrespondence, where the preset correspondence includes acorrespondence between a preamble mode and a data rate.

Optionally, in an embodiment, the second WUP includes a MAC headerfield, the MAC header field includes an identifier information field,the identifier information field is used to carry identifier informationof the receive end device, and a quantity of information bits includedin the identifier information field is positively correlated with amagnitude of the second data rate.

It should be understood that the receive end device 200 according tothis embodiment of this application may correspond to the receive enddevice 20 in the embodiments of this application, and may correspond toa corresponding entity for executing the method for transmitting awake-up packet in a communications system according to the embodimentsof this application, and the foregoing and other operations and/orfunctions of each module in the receive end device 200 are respectivelyused to implement corresponding procedures in the method 100. Forbrevity, details are not described herein again.

Therefore, the receive end device in a communications system accordingto this embodiment of this application receives wake-up packets sent bythe transmit end device by using different data rates, and the transmitend device can determine, based on a specific transmission condition ina communication process, a proper data rate for sending a wake-uppacket, thereby improving efficiency of transmitting the wake-up packet.

It should be understood that “one embodiment” or “an embodiment”mentioned in the entire specification does not mean that particularfeatures, structures, or characteristics related to this embodiment areincluded in at least one embodiment of this application. Therefore, “inone embodiment” or “in an embodiment” appearing throughout thisspecification does not necessarily refer to a same embodiment. Inaddition, these particular features, structures, or characteristics maybe combined in one or more embodiments in any appropriate manner.

It should be understood that the term “and/or” in this specificationdescribes only an association relationship between associated objectsand represents that three relationships may exist. For example, A and/orB may represent the following three cases: Only A exists, both A and Bexist, and only B exists. In addition, the character “/” in thisspecification generally indicates an “or” relationship between theassociated objects.

It should be understood that sequence numbers of the foregoing processesdo not mean execution sequences in various embodiments of thisapplication. The execution sequences of the processes should bedetermined based on functions and internal logic of the processes, andshould not be construed as any limitation on the implementationprocesses of the embodiments of this application.

A person of ordinary skill in the art may be aware that, in combinationwith the embodiments disclosed in this specification, method steps andunits may be implemented by electronic hardware, computer software, or acombination thereof. To clearly describe the interchangeability betweenthe hardware and the software, the foregoing has generally describedsteps and compositions of each embodiment according to functions.Whether the functions are performed by hardware or software depends onparticular applications and design constraint conditions of thetechnical solutions. A person of ordinary skill in the art may usedifferent methods to implement the described functions for eachparticular application, but it should not be considered that theimplementation goes beyond the scope of this application.

Methods or steps described in the embodiments disclosed in thisspecification may be implemented by hardware, a software programexecuted by a processor, or a combination thereof. The software programmay be deployed in a random access memory (Random Access Memory, RAM), amemory, a read-only memory (Read-Only Memory, ROM), an electricallyprogrammable read-only memory (Electrically Programmable Read-OnlyMemory, EPROM), an electrically erasable programmable read-only memory(Electrically Erasable Programmable Read-Only Memory, EEPROM), aregister, a hard disk, a removable disk, a compact disc read-only memory(Compact Disc Read-Only Memory, CD-ROM), or any other form of storagemedium known in the technical field.

In the several embodiments provided in this application, it should beunderstood that the disclosed system, apparatus, and method may beimplemented in other manners. For example, the described apparatusembodiment is merely an example. For example, the unit division ismerely logical function division and may be other division in actualimplementation. For example, a plurality of units or components may becombined or integrated into another system, or some features may beignored or not performed.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one position, or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected based on actualrequirements to achieve the objectives of the solutions of theembodiments.

In addition, functional units in the embodiments of this application maybe integrated into one processing unit, or each of the units may existalone physically, or two or more units are integrated into one unit.

This application is described in detail with reference to the accompanydrawings and in combination with the example embodiments, but thisapplication is not limited thereto. Various equivalent modifications orreplacements can be made to the embodiments of this application by aperson of ordinary skill in the art without departing from essence ofthis application, and the modifications or replacements shall fallwithin the scope of this application.

1-64. (canceled)
 65. A transmit end device the transmit end devicecomprises: a transceiver, configured to send a first wake-up packet WUPto the wake-up receiver of a receive end device by using a first datarate; and the transceiver is further configured to send a second WUP tothe wake-up receiver of a receive end device by using the second datarate.
 66. The transmit end device according to claim 65, the second WUPcomprises a preamble field and a data field, wherein the preamble fieldcorresponds to a preamble mode, the preamble mode corresponds to a datarate.
 67. The transmit end device according to claim 65, the transmitend device further comprises: a processor, configured to determine thesecond data rate before sending the second WUP to the wake-up receiverof a receive end device by using the second data rate.
 68. The transmitend device according to claim 67, wherein in the aspect of sending thefirst wake-up packet to the wake-up receiver of a receive end device byusing the first data rate, the transceiver module is specificallyconfigured to: send the first WUP to the wake-up receiver of a receiveend by using a first symbol rate; in the aspect of determining thesecond data rate, the processor, is specifically configured to determinea second symbol rate; and in the aspect of sending the second WUP to thewake-up receiver of a receive end device by using the second data rate,the transceiver is specifically configured to send the second WUP to thewake-up receiver of a receive end device by using the second symbolrate.
 69. The transmit end device according to claim 67, wherein in theaspect of sending the first wake-up packet WUP to the wake-up receiverof a receive end device by using the first data rate, the transceiver isspecifically configured to send the first WUP to the wake-up receiver ofa receive end device by using a first modulation and coding scheme; inthe aspect of determining the second data rate, the processor isspecifically configured to determine a second modulation and codingscheme; and in the aspect of sending the second WUP to the wake-upreceiver of a receive end device by using the second data rate, thetransceiver is specifically configured to send the second WUP to thewake-up receiver of a receive end device by using the second modulationand coding scheme.
 70. The transmit end device according to claim 67,wherein in the aspect of determining the second data rate, the processoris specifically configured to: determine the second data rate based on adata rate used when the transmit end device sends data to a maintransceiver of a receive end device.
 71. The transmit end deviceaccording to claim 67, wherein in the aspect of determining the seconddata rate, the processor is specifically configured to: determine thesecond data rate based on an operating frequency band of a maintransceiver of a receive end device and/or an operating frequency bandof the wake-up receiver of a receive end device.
 72. The transmit enddevice according to claim 67, wherein in the aspect of determining thesecond data rate, the processor is specifically configured to: determinea symbol length corresponding to the second data rate based on amultipath delay spread.
 73. The transmit end device according to claim67, wherein in the aspect of determining the second data rate, thetransceiver is configured to: receive feedback information sent by themain transceiver of a receive end device; and the processor isconfigured to determine the second data rate based on the feedbackinformation.
 74. The transmit end device according to claim 73, whereinthe feedback information comprises first information used to indicate asignal-to-noise ratio on an operating frequency of the main transceiverof a receive end device and/or the wake-up receiver of a receive enddevice; and in the aspect of determining the second data rate based onthe feedback information, the processor is specifically configured to:determine the second data rate based on the first information and acorrespondence between a signal-to-noise ratio and a data rate.
 75. Areceive end device, the receive end device comprises a wake-up receiver,wherein the wake-up receiver is configured to receive a first wake-uppacket WUP sent by the transmit end device by using a first data rate;the wake-up receiver is further configured to receive a second WUP sentby the transmit end device by using a second data rate.
 76. The receiveend device according to claim 75, the receive end device furthercomprises a processor, the processor is configured to determine thesecond data rate based on a preamble field of the second WUP and parsethe second WUP based on the second data rate, wherein the second WUPcomprises the preamble field and a data field, wherein the preamblefield corresponds to a preamble mode, the preamble mode corresponds to adata rate.
 77. The receive end device according to claim 76, wherein inthe aspect of receiving the first wake-up packet WUP sent by thetransmit end device by using the first data rate, the wake-up receivermodule is specifically configured to receive the first WUP sent by thetransmit end device by using a first symbol rate; in the aspect ofreceiving the second WUP sent by the transmit end device by using thesecond data rate, the wake-up receiver is configured to receive thesecond WUP sent by the transmit end device by using the second symbolrate; in the aspect of determining the second data rate, the processoris specifically configured to determine the second symbol rate; and inthe aspect of parsing the second WUP based on the second data rate, theprocessor is specifically configured to parse the second WUP based onthe second symbol rate.
 78. The receive end device according to claim76, wherein in the aspect of receiving the first wake-up packet WUP sentby the transmit end device by using the first data rate, the wake-upreceiver is specifically configured to receive the first WUP sent by thetransmit end device by using a first modulation and coding scheme; inthe aspect of receiving the second WUP sent by the transmit end deviceby using the second data rate, the wake-up receiver is specificallyconfigured to receive the second WUP sent by the transmit end device byusing the second modulation and coding scheme; in the aspect ofdetermining the second data rate, the processor is specificallyconfigured to determine the second modulation and coding scheme; and inthe aspect of parsing the second WUP based on the second data rate, theprocessor is specifically configured to parse the second WUP based onthe second modulation and coding scheme.
 79. The receive end deviceaccording to claim 76, the receive end device further comprises a maintransceiver, the main transceiver is configured to: send feedbackinformation to the transmit end device.
 80. The receive end deviceaccording to claim 79, wherein the feedback information comprises firstinformation used to indicate a signal-to-noise ratio on an operatingfrequency of the main transceiver and/or the wake-up receiver.
 81. Thereceive end device according to claim 79, wherein the feedbackinformation comprises second information used to indicate a power of thefirst WUP when the first WUP arrives at the wake-up receiver; or thefeedback information comprises third information used to indicate asignal-to-noise ratio of the first WUP at the wake-up receiver; or thefeedback information comprises fourth information used to indicate apacket error rate of the first WUP at the wake-up receiver.
 82. Thereceive end device according to claim 79, wherein in the aspect ofsending the feedback information to the transmit end device, the maintransceiver is configured to: send a medium access control MAC frame tothe transmit end device, wherein the MAC frame carries the feedbackinformation.
 83. The receive end device according to claim 82, whereinin the aspect of sending the medium access control MAC frame to thetransmit end device, the main transceiver is specifically configured to:send a quality of service QoS data frame to the transmit end device,wherein the QoS data frame comprises a high throughput control field,and the high throughput control field carries the feedback information;or send a QoS null frame to the transmit end device, wherein the QoSnull frame comprises a high efficiency aggregated control field, and thehigh efficiency aggregated control field carries the feedbackinformation; or send a beamforming report to the transmit end device,wherein the beamforming report comprises a feedback field, and thefeedback field carries the feedback information.
 84. The receive enddevice according to claim 82, wherein in the aspect of receiving thesecond WUP sent by the transmit end device by using the second datarate, the wake-up receiver is specifically configured to: receive aplurality of modulation symbols sent by the transmit end device, whereinthe plurality of modulation symbols are obtained by the transmit enddevice by modulating an information bit in the second WUP based on thesecond data rate, and the plurality of modulation symbols comprise afirst modulation symbol whose symbol energy is 0 and a second modulationsymbol whose symbol energy is not 0.